JP4320356B2 - Thermally expansible microspheres, production method and use thereof - Google Patents

Description

  The present invention relates to a thermally expandable microsphere, a method for producing the same, and an application thereof.

Thermally expandable microspheres having a structure in which a thermoplastic resin is used as an outer shell and a foaming agent is enclosed in the outer shell are generally referred to as thermally expandable microcapsules. As the thermoplastic resin, a vinylidene chloride copolymer, an acrylonitrile copolymer, an acrylic copolymer, or the like is usually used. Moreover, hydrocarbons, such as isobutane and isopentane, are mainly used as a foaming agent (refer patent document 1).
For example, 80% by weight or more of nitrile monomer, 20% by weight or less of non-nitrile monomer, and a thermoplastic resin obtained from a component containing a crosslinking agent are used as heat-expandable microcapsules having high heat resistance. Patent Document 2 discloses a thermally expandable microcapsule used as a shell. The production method includes colloidal silica as a dispersion stabilizer (suspension agent), diethanolamine-adipic acid condensation product as an auxiliary stabilizer, and an aqueous dispersion medium containing a polymerization aid. This is a method for producing thermally expandable microcapsules by suspension polymerization of a polymerizable mixture containing a polymerizable monomer and a polymerization initiator.
The polymerization aid is generally used for suppressing the generation of an emulsion polymer in an aqueous system in suspension polymerization and for preventing scale. In recent years, in the method for producing thermally expandable microcapsules, in addition to the purpose of suppressing the generation of emulsion polymers in water and preventing scale, various types of thermally expandable microcapsules and hollow fine particles obtained by further thermal expansion are obtained. It has been desired to develop a polymerization aid capable of improving physical properties. Patent Document 3 discloses a method for producing a thermally expanded microcapsule by using a so-called polymerization inhibitor such as ascorbic acid or alkali metal nitrite as a polymerization aid instead of potassium dichromate. . Patent Document 3 describes that when a thermally expandable microcapsule obtained by this method is thermally expanded, a foam having sharp and uniform foam (hollow fine particles) can be obtained. However, improvement in physical properties such as expansion ratio is not sufficient, and ascorbic acids are not preferable because they have low thermal stability and are decomposed during the polymerization reaction to lose their properties as a polymerization inhibitor. In addition, for alkali metal nitrites, the standard value for the amount of groundwater contained in the Water Pollution Control Law enforcement regulations for implementing the Water Pollution Control Law in Japan is set. There is a problem that may occur. Therefore, ascorbic acids and alkali metal nitrites cannot sufficiently improve the physical properties of the resulting heat-expandable microcapsules and the hollow microparticles obtained by further thermal expansion, and the above problems occur in use. However, it is not a satisfactory polymerization aid at present.
Conventionally, with regard to research and development of hollow microparticles obtained by thermally expanding thermally expandable microcapsules, various types and blending ratios of thermoplastic resins and foaming agents constituting the hollow microparticles are examined, and various physical properties are investigated. Improvement has been mainly studied.
Regarding the improvement of repeated compression durability of hollow microparticles, for example, Patent Documents 4 and 5 disclose thermally expanded microparticles having polar groups on their surfaces as hollow microparticles that are difficult to be destroyed during mixing and molding of a ceramic composition. Capsules are introduced. However, the improvement of the crushing resistance at the time of mixing and molding is insufficient.
Further, Patent Document 6 has an outer shell formed of a polymer obtained from a specific monomer composition and a cross-linking agent as hollow fine particles for lightweight cement products, and has a thermal expansion ratio of 20 times to 100 times. Hollow microparticles obtained by heating and foaming conductive microcapsules are described. However, this hollow fine particle is also insufficient in improving the durability.
Furthermore, Patent Document 7 discloses a mixture of hollow microparticles and thermally expandable microcapsules that are difficult to break during mixing and forming of a ceramic composition. However, the particle size distribution of the mixture is merely sharpened, and cannot be said to be an essential improvement in durability.
As described above, various studies have been made on the repeated compression durability of hollow fine particles, but the present situation is that hollow fine particles having sufficiently improved repeated compression durability have not been obtained. The hollow microparticles obtained by thermally expanding the thermally expandable microcapsules manufactured by the manufacturing method described in Patent Document 3 also have low repeated compression durability.
US Pat. No. 3,615,972 Japanese Unexamined Patent Publication No. Sho 62-286534 Japanese Patent Laid-Open No. 11-209504 Japanese Unexamined Patent Publication No. 2003-327482 Japanese Unexamined Patent Publication No. 2003-327483 Japanese Unexamined Patent Publication No. 2004-131361 Japanese Unexamined Patent Publication No. 2005-067943

  An object of the present invention is to provide a thermally expandable microsphere that is a hollow microparticle having a high expansion ratio and having excellent repeated compression durability when thermally expanded, a method for producing the same, and a use thereof.

As a result of intensive studies to solve the above problems, the present inventors have found that 1) the above-described problems can be solved if the thermally expandable microspheres have specific physical properties, and 2) the thermally expandable microspheres have a specific water solubility. The present invention has been achieved by confirming that it can be produced by dispersing and polymerizing an oily mixture containing a polymerizable component and a foaming agent in an aqueous dispersion medium containing a compound.
The thermally expandable microsphere according to the present invention is a thermally expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent encapsulated in the outer shell and having a boiling point equal to or lower than the softening point of the thermoplastic resin. Thus, the expansion ratio at the time of maximum expansion is 50 times or more, and the repeated compression durability of the hollow fine particles obtained by thermal expansion is 75% or more.
The method for producing thermally expandable microspheres according to the present invention comprises a thermally expandable microsphere comprising an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and having a boiling point equal to or lower than the softening point of the thermoplastic resin. A method of manufacturing a sphere,
Water-soluble metal salts and / or hydrates thereof; water-soluble polyphenols; water-soluble vitamin Bs; and hydrophilic functional groups and heteroatoms selected from hydroxyl groups, carboxylic acid (salt) groups, and phosphonic acid (salt) groups Containing a polymerizable component and the blowing agent in an aqueous dispersion medium containing at least one water-soluble compound selected from water-soluble 1,1-substituted compounds having a structure bonded to the same carbon atom. A step of dispersing an oily mixture and polymerizing the polymerizable component contained in the oily mixture;
Another method for producing thermally expandable microspheres according to the present invention includes a thermal expansion composed of an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and having a boiling point equal to or lower than the softening point of the thermoplastic resin. A method for producing a conductive microsphere comprising scandium, cerium, titanium, zirconium, hafnium, vanadium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, nickel, silver, gold, Aqueous dispersion containing 0.001 to 100 ppm of ions of at least one metal selected from zinc, cadmium, boron, aluminum, gallium, indium, thallium, tin, lead, arsenic, antimony and bismuth and 0.001 ppm or more of halogen ions Contains a polymerizable component and the foaming agent in the medium Sexual mixture is dispersed, comprising the step of polymerizing the polymerizable component contained in the oily mixture.
The hollow fine particles according to the present invention can be obtained by heating and expanding the thermally expandable microspheres and / or the thermally expandable microspheres obtained by the method for producing the thermally expandable microspheres.
The composition according to the present invention is a composition containing a base material component and the thermally expandable microspheres and / or the hollow fine particles.
The molded product according to the present invention is obtained by molding the above composition.

The thermally expandable microspheres of the present invention have a high expansion ratio, and hollow particles having excellent repeated compression durability when thermally expanded can be obtained.
In the method for producing thermally expandable microspheres of the present invention, thermally expandable microspheres that have high expansion ratio and become hollow fine particles having excellent repeated compression durability when thermally expanded can be efficiently produced. .
Since the hollow fine particles of the present invention are obtained using the above-mentioned thermally expandable microspheres as raw materials, they have excellent repeated compression durability.
Since the composition and the molded product of the present invention both contain the hollow fine particles, they have excellent repeated compression durability.

It is the schematic which shows an example of the thermally expansible microsphere of this invention. It is the schematic of the foaming process part of the manufacturing apparatus used for the manufacturing method of a hollow microparticle for repeated compression durability measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot air nozzle 2 Refrigerant flow 3 Overheating prevention cylinder 4 Dispersion nozzle 5 Collision plate 6 Gas fluid containing thermally expansible microsphere 7 Gas flow 8 Hot air flow 11 Outer shell made of thermoplastic resin 12 Foaming agent

に基づいている。
上記金属の原子価については、特に限定はないが、本願発明の効果が十分に得られ、活性が強すぎず、弱すぎず、つまり、適度あるという点で、いろいろな価数のうちで３価が好ましい。その作用・機構等は必ずしも明らかではないが、３価金属は、油性である重合性成分のラジカル重合機構に直接関与するものではなく、水中で溶解した電子受容体として働き、重合時に懸濁液滴の表面で電子受容する。その結果、油性混合物の重合促進をはかり、受容した電子を水系に放出して重合反応に関与していると考えられる。
水溶性金属塩としては、特に限定はないが、金属ハロゲン化物を挙げることができ、分子内に有機基をさらに含有していてもよい。金属ハロゲン化物を構成するハロゲンについては、特に限定はないが、フッ素、塩素、臭素、ヨウ素およびアスタチンから選ばれた少なくとも一種を挙げることができ、フッ素、塩素および臭素から選ばれた少なくとも一種が好ましく、塩素および／または臭素であるとさらに好ましく、塩素であると特に好ましい。
金属ハロゲン化物の分子内に含有していてもよい有機基としては、たとえば、アルキル基、アリール基、ヒドロキシル基、アルコキシ基、アシルオキシ基、アミノ基、ニトロ基、シアノ基、フェニル基、フェノキシ基、トリル基、ベンジル基、カルボキシ基、チオカルボキシ基、チオカルボニル基、チオニル基、チオアセチル基、メルカプト基、スルフォ基、スルフィノ基、メシル基、トシル基、トリフラート基、トリフリルイミド基、アセチルアセトナート基等を挙げることができる。
金属ハロゲン化物としては、３価金属のハロゲン化物（金属（ＩＩＩ）ハロゲン化物）が好ましい。金属（ＩＩＩ）ハロゲン化物の具体例としては、たとえば、塩化アルミニウム（ＩＩＩ）、塩化アンチモン（ＩＩＩ）、塩化ガリウム（ＩＩＩ）、塩化金（ＩＩＩ）、塩化セリウム（ＩＩＩ）、塩化タリウム（ＩＩＩ）、塩化タングステン（ＩＩＩ）、塩化タンタル（ＩＩＩ）、塩化チタン（ＩＩＩ）、塩化鉄（ＩＩＩ）塩化ニッケル（ＩＩＩ）、塩化バナジウム（ＩＩＩ）塩化ビスマス（ＩＩＩ）、３塩化ヒ素（ＩＩＩ）、塩化ルテニウム（ＩＩＩ）、塩化レニウム（ＩＩＩ）、塩化オスミウム（ＩＩＩ）、等の金属塩化物；フッ化アルミニウム（ＩＩＩ）、フッ化マンガン（ＩＩＩ）、等の金属フッ化物；臭化アルミニウム（ＩＩＩ）、臭化タリウム（ＩＩＩ）等の金属臭化物等を挙げることができる。これらの金属ハロゲン化物は、１種または２種以上を併用してもよい。
水溶性金属塩では、たとえば、無水塩化アルミニウムのように、水と容易に反応し塩化水素を発生し、ｐＨ等の条件によっては水不溶性の水酸化物が生成するものがある。このような場合には、水中で溶解しているアルミニウム（ＩＩＩ）の濃度が不明になる点や、塩化水素が金属製反応器を腐食させる点があるので、水溶性金属塩の水和物が好ましい。
水溶性金属塩の水和物では、水溶性金属塩の金属元素を中心に水が配位した錯体構造をとっている。水溶性金属塩の水和物としては、特に限定はないが、上記で説明した金属ハロゲン化物の水和物を挙げることができる。これらの水溶性金属塩の水和物は、１種または２種以上を併用してもよい。
金属ハロゲン化物の水和物の具体例としては、たとえば、塩化アルミニウム（ＩＩＩ）６水和物、塩化クロム（ＩＩＩ）ｎ水和物、塩化セリウム（ＩＩＩ）ｎ水和物、塩化タリウム（ＩＩＩ）４水和物、塩化チタン（ＩＩＩ）ｎ水和物、フッ化アルミニウム（ＩＩＩ）ｎ水和物等を挙げることができる。なお、ｎは水和数であり、金属元素に配位した水の配位数を示す。
水溶性化合物（２）：水溶性ポリフェノール類
水溶性ポリフェノール類としては、特に限定はないが、たとえば、フラボノイド、カテキン、タンニン、イソフラボン、アントシアニン、ルチン、クロロゲン酸、没食子酸、リコピン、ケルセチン、ミリセチン、タクシフォソン、これらの誘導体や多量体、これらを含有する緑茶抽出物、赤ワイン抽出物、カカオ抽出物、ひまわり種子抽出物等を挙げることができる。なお、タンニンとしては、加水分解可能なガロタンニン、ジフェニルメチロリッド型タンニン、縮合型のフロバフェン生成型タンニン等があり、このいずれでもよい。タンニン酸は加水分解可能なタンニンの混合物である。これらの水溶性ポリフェノール類は、１種または２種以上を併用してもよい。
水溶性化合物（３）：水溶性ビタミンＢ類
水溶性ビタミンＢ類としては、特に限定はないが、たとえば、ビタミンＢ_１（チアミン）、ビタミンＢ_２（リボフラビン）、ビタミンＢ_６（ピリドキシン）、ビタミンＢ_１２（コバラミン）、これらビタミンＢ類のヌクレオチドやヌクレオシド等への誘導体、または、硝酸塩、塩酸塩等の無機酸塩等を挙げることができる。これらの水溶性ビタミンＢ類は、１種または２種以上を併用してもよい。
水溶性化合物（４）：水酸基、カルボン酸（塩）基およびホスホン酸（塩）基から選ばれた親水性官能基とヘテロ原子とが同一の炭素原子に結合した構造を有する水溶性１，１−置換化合物類
水溶性１，１−置換化合物類としては、特に限定はないが、たとえば、親水性官能基がカルボン酸（塩）基で、ヘテロ原子が窒素原子である構造を有したアミノポリカルボン酸（塩）類や、親水性官能基がホスホン酸（塩）基で、ヘテロ原子が窒素原子である構造を有したアミノポリホスホン酸（塩）類等を挙げることができる。
アミノポリカルボン酸（塩）類としては、特に限定はないが、たとえば、エチレンジアミン四酢酸（その塩も含む）、ヒドロキシエチルエチレンジアミン三酢酸（その塩も含む）、ジエチレントリアミン五酢酸（その塩も含む）、ジヒドロキシエチルエチレンジアミン二酢酸（その塩も含む）、１，３−プロパンジアミン四酢酸（その塩も含む）、ジエチレントリアミン五酢酸（その塩も含む）、トリエチレンテトラアミン六酢酸（その塩も含む）、ニトリロ三酢酸（その塩も含む）、グルコン酸（その塩も含む）、ヒドロキシエチルイミノ二酢酸（その塩も含む）、Ｌ−アスパラギン酸−Ｎ，Ｎ−ジ二酢酸（その塩も含む）、ジカルボキシメチルグルタミン酸（その塩も含む）、１，３−ジアミノ−２−ヒドロキシプロパン四酢酸（その塩も含む）、ジヒドロキシエチルグリシン（その塩も含む）等のアミノポリカルボン酸；これらの金属塩；これらのアンモニウム塩等を挙げることができる。これらのアミノポリカルボン酸（塩）類は、１種または２種以上を併用してもよい。
上記で例示したエチレンジアミン四酢酸（その塩も含む）の化学構造を以下の化学式（１）に示す。

（但し、Ｍ^１〜Ｍ^４は、いずれも水素原子、アルカリ金属、アルカリ土類金属、遷移金属、アンモニウム基および１〜４級アミン基から選ばれ、同一であってもよく異なっていてもよい。）
上記で例示したジエチレントリアミン五酢酸（その塩も含む）の化学構造を以下の化学式（２）に示す。

（但し、Ｍ^１〜Ｍ^５は、いずれも水素原子、アルカリ金属、アルカリ土類金属、遷移金属、アンモニウム基および１〜４級アミン基から選ばれ、同一であってもよく異なっていてもよい。）
アミノポリホスホン酸（塩）類としては、特に限定はないが、たとえば、アミノトリメチレンホスホン酸（その塩も含む）、ヒドロキシエタンホスホン酸（その塩も含む）、ヒドロキシエチリデン二ホスホン酸（その塩も含む）、ジヒドロキシエチルグリシン（その塩も含む）、ホスホノブタン三酢酸（その塩も含む）、メチレンホスホン酸（その塩も含む）ニトリロトリスメチレンホスホン酸（その塩も含む）、エチレンジアミン四（メチレンホスホン酸）（その塩も含む）等のアミノポリホスホン酸；これらの金属塩；これらのアンモニウム塩等を挙げることができる。これらのアミノポリホスホン酸（塩）類は、１種または２種以上を併用してもよい。
上記アミノポリカルボン酸塩類やアミノポリホスホン酸塩類とは、アミノポリカルボン酸やアミノポリホスホン酸の金属塩類、アミン塩類、アンモニウム塩類等を意味する。
上記金属塩類は、酸性基であるカルボン酸基やホスホン酸基の少なくとも１つのプロトンが金属原子で置き換わった化合物である。金属原子としては、たとえば、リチウム、ナトリウム、カリウム等のアルカリ金属（周期表における１族金属）；ベリリウム、マグネシウム、カルシウム、ストロンチウム、バリウム等のアルカリ土類金属（周期表における２族金属）；鉄、銅、マンガン、亜鉛、コバルト等の遷移金属等を挙げることができる。得られる金属塩類が入手しやすく食品添加物として用いられることもあり、これらの金属原子なかでも、ナトリウム、カリウム等が好ましい。
上記アミン塩類とは、酸性基であるカルボン酸基やホスホン酸基の少なくとも１つのプロトンがアミンと反応して得られた化合物等である。アミン塩類は、酸性基であるカルボン酸基やホスホン酸基の少なくとも１つのプロトンが１〜４級アミン基で置き換わった化合物と表現することもできる。ここで、１級アミン基とは１級アミンにプロトンが反応して得られる全体として＋１の電荷を帯びた基であり、２級アミン基とは２級アミンにプロトンが反応して得られる全体として＋１の電荷を帯びた基であり、３級アミン基とは３級アミンにプロトンが反応して得られる全体として＋１の電荷を帯びた基であり、４級アミン基とは３級アミン基のプロトンが炭化水素基で置換されており、全体として＋１の電荷を帯びた基である。
１〜３級アミン基の原料となる１〜３級アミンとしては、炭素原子数１〜５の（モノ、ジまたはトリ）アルキルアミン（例えば、エチルアミン、プロピルアミン等）、炭素原子数２〜１０の（モノ、ジまたはトリ）アルカノールアミン（例えば、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、モノイソプロパノールアミン、ジイソプロパノールアミン、トリイソプロパノールアミン、シクロヘキシルジエタノールアミン等）、モルホリン、炭素原子数５〜２０のシクロアルキルアミン（例えば、ジシクロヘキシルアミン等）、３，３−ジメチルプロパンジアミン等がある。
４級アミン基としては、たとえば、ドデシルトリメチルアンモニウム、ヤシアルキルトリメチルアンモニウム、ヘキサデシルトメチルアンモニウム、牛脂アルキルトリメチルアンモニウム、オクタデシルトリメチルアンモニウム、ベヘニルトリメチルアンモニウム、ヤシアルキルジメチルベンジルアンモニウム、テトラデシルジメチルベンジンアンモニウム、ヤシアルキルジメチルベンジルアンモニウム、オクタデシルジメチルベンジルアンモニウム、ヤシアルキルアンモニウム、テトラデシルアンモニウム、オクタデシルアンモニウム、トリエチルメチルアンモニウム、ジオレイルジメチルアンモニウム、ジデシルジメチルアンモニウム、トリエチルメチルアンモニウム等を挙げることができる。
上記アンモニウム塩類とは、酸性基であるカルボン酸基やホスホン酸基の少なくとも１つのプロトンがアンモニアと反応して得られた化合物である。アンモニウム塩類は、プロトンがアンモニウム基（−ＮＨ_４ ^＋）で置き換わった化合物と表現することもできる。
また、その他の水溶性１，１−置換化合物類としては、特に限定はないが、たとえば、親水性官能基がカルボン酸（塩）基で、ヘテロ原子が窒素原子である構造を有した２−カルボキシピリジン、オロチン酸、キノリン酸、ルチジン酸、イソシンコメロン酸、ジピコリン酸、ベルベロン酸、フサル酸、オロト酸等；親水性官能基が水酸（塩）基で、ヘテロ原子が窒素原子である構造を有した２−ヒドロキシピリジン、６−ヒドロキシニコチン酸、シトラジン酸等；親水性官能基がカルボン酸（塩）基で、ヘテロ原子が硫黄原子である構造を有したチオジグリコール酸等の化合物を挙げることができる。
水溶性１，１−置換化合物類において、親水性官能基がカルボン酸（塩）基および／またはホスホン酸（塩）基であり、ヘテロ原子が窒素原子および／または硫黄原子であると、好ましい。
水溶性化合物が、塩化チタン（ＩＩＩ）、塩化鉄（ＩＩＩ）、塩化アルミニウム（ＩＩＩ）６水和物、塩化アンチモン（ＩＩＩ）、塩化ビスマス（ＩＩＩ）等の水溶性化合物（１）；タンニン、没食子酸等の水溶性化合物（２）；ビタミンＢ_２、ビタミンＢ_６等の水溶性化合物（３）；エチレンジアミン四酢酸（その塩も含む）、ヒドロキシエチルエチレンジアミン三酢酸（その塩も含む）、ジエチレントリアミン五酢酸（その塩も含む）、ジヒドロキシエチルエチレンジアミン二酢酸（その塩も含む）、１，３−プロパンジアミン四酢酸（その塩も含む）、ジエチレントリアミン五酢酸（その塩も含む）、トリエチレンテトラアミン六酢酸（その塩も含む）、ニトリロ三酢酸（その塩も含む）、グルコン酸（その塩も含む）、ヒドロキシエチルイミノ二酢酸（その塩も含む）、Ｌ−アスパラギン酸−Ｎ，Ｎ−ジ二酢酸（その塩も含む）、ジカルボキシメチルグルタミン酸（その塩も含む）、１，３−ジアミノ−２−ヒドロキシプロパン四酢酸（その塩も含む）、ジヒドロキシエチルグリシン（その塩も含む）、アミノトリメチレンホスホン酸（その塩も含む）、ヒドロキシエタンホスホン酸（その塩も含む）、ジヒドロキシエチルグリシン（その塩も含む）、ホスホノブタン三酢酸（その塩も含む）、メチレンホスホン酸（その塩も含む）ニトリロトリスメチレンホスホン酸（その塩も含む）、２−カルボキシピリジン、オロチン酸、キノリン酸、ルチジン酸、イソシンコメロン酸、ジピコリン酸、ベルベロン酸、フサル酸、オロト酸、２−ヒドロキシピリジン、６−ヒドロキシニコチン酸、シトラジン酸、チオジグリコール酸等の水溶性化合物（４）から選ばれた少なくとも一種であると、入手しやすく安定であるという理由から好ましい。
また、水溶性化合物が、塩化アルミニウム（ＩＩＩ）６水和物、塩化アンチモン（ＩＩＩ）、塩化ビスマス（ＩＩＩ）、ビタミンＢ_６、２−カルボキシピリジン、２−ヒドロキシピリジン、６−ヒドロキシニコチン酸、オロチン酸、チオジグリコール酸、エチレンジアミン四酢酸（その塩も含む）およびジエチレントリアミン五酢酸（その塩も含む）から選ばれた少なくとも一種であるとさらに好ましい。
また、水溶性化合物が、塩化アルミニウム（ＩＩＩ）６水和物、２−カルボキシピリジン、２−ヒドロキシピリジン、６−ヒドロキシニコチン酸、オロチン酸、エチレンジアミン四酢酸（その塩も含む）およびジエチレントリアミン五酢酸（その塩も含む）から選ばれた少なくとも一種であると特に好ましい。
水溶性化合物（１）〜（４）のうちでも、水溶性化合物（１）および／または水溶性化合物（４）が好ましい。水溶性化合物を少なくとも２つ併用して重合する場合、以下に示す３つの組合せ（ａ）〜（ｃ）のうちのいずれかの組合せであると、水溶性化合物を１つだけ使用して重合する場合よりも、最大膨張時の膨張倍率、繰り返し圧縮耐久性、重合時において生成する熱膨脹性微小球の凝集や重合反応器内のスケール発生を防止する作用効果の点で、優れる。
（ａ）水溶性化合物（１）を少なくとも２つ含む組合せ
（ｂ）水溶性化合物（４）を少なくとも２つ含む組合せ
（ｃ）水溶性化合物（１）１つおよび水溶性化合物（４）１つを少なくとも含む組合せ
水性分散媒中に含まれる水溶性化合物の量については、特に限定はないが、重合性成分１００重量部に対して、好ましくは０．０００１〜１．０重量部、さらに好ましくは０．０００３〜０．８重量部、特に好ましくは０．００１〜０．５重量部である。水溶性化合物の量が少なすぎると、水溶性化合物による効果が十分に得られないことがある。また、水溶性化合物の量が多すぎると、重合速度が低下したり、原料である重合性成分の残存量が増加することがある。
上述したとおり、水溶性化合物は、重合助剤として使用される成分であり、重合時において生成する熱膨張性微小球の凝集や重合反応器内のスケール発生（具体的には、重合性成分の重合において、重合物が熱膨張性微小球の外殻表面に強固に付着することによる凝集体や重合物による濾過時の目詰まり、重合反応器内壁への重合物の付着）を防止する作用を本来的に有している。本発明の製造方法では、このような水溶性化合物を使用しているので、重合時において生成する熱膨張性微小球の凝集や重合反応器内のスケール発生を防止する点でも優れている。
本発明において、水溶性化合物は他の重合助剤と併用してもよい。他の重合助剤としては、重クロム酸アンモニウム（二クロム酸アンモニウム）、重クロム酸ナトリウム（二クロム酸ナトリウム）、重クロム酸カリウム（二クロム酸カリウム）等の重クロム酸塩（二クロム酸塩）；亜硝酸ナトリウム、亜硝酸カリウム等の亜硝酸アルカリ金属塩；水溶性アスコルビン酸およびその誘導体等のラジカル禁止剤が挙げられる。亜硝酸アルカリ金属塩については、水質汚濁防止法を実施するための水質汚濁防止法施行規則において、地下水に含まれる有害物質の量について基準値が決められており、亜硝酸性窒素および硝酸性窒素の合計量について、１０ｐｐｍという基準値が定められている。したがって、従来の熱膨張性微小球の製造方法で使用されている亜硝酸塩類については、反応廃液がこの濃度を超えた場合は、排出時に多量の水で希釈したり、活性炭やイオン交換樹脂等を用いて吸着処理を施したりする必要がある。
本発明の製造方法では、水溶性化合物を含有する水性分散媒中で重合性成分を重合するために、製造時に仕込んだ発泡剤が無駄なく有効に熱膨張性微小球に内包されるという効果も得られる。本発明の製造方法においては、実施例で具体的な計算方法を示す内包効率（％）が、好ましくは８８％以上であり、さらに好ましくは９０％以上であり、特に好ましくは９５％以上である。
水性分散媒は、水溶性化合物以外に、上記で説明した電解質や、分散安定剤や分散安定補助剤を含有していてもよい。
分散安定剤としては、特に限定はないが、たとえば、コロイダルシリカ、コロイダル炭酸カルシウム、水酸化マグネシウム、水酸化カルシウム、水酸化アルミニウム、水酸化第二鉄、硫酸カルシウム、硫酸バリウム、蓚酸カルシウム、メタケイ酸カルシウム、炭酸カルシウム、炭酸バリウム、炭酸マグネシウム、リン酸カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛等のリン酸塩、ピロリン酸カルシウム、ピロリン酸アルミニウム、ピロリン酸亜鉛等のピロリン酸塩、アルミナゾル等の難水溶性無機化合物の分散安定剤を挙げることができる。これらの分散安定剤は、１種または２種以上を併用してもよく、得られる熱膨張性微小球の粒子径と重合時の分散安定性等を考慮してその種類が適宜選択される。なかでも、第三リン酸カルシウム、複分解生成法により得られるピロリン酸マグネシウム、ピロリン酸カルシウムや、コロイダルシリカが好ましい。
分散安定剤の配合量については、目的とする粒子径により適宜決定され、特に限定されないが、重合性成分１００重量部に対して、好ましくは０．１〜２０重量部、さらに好ましくは２〜１０重量部である。
分散安定補助剤としては、特に限定はないが、たとえば、高分子タイプの分散安定補助剤、カチオン性界面活性剤、アニオン性界面活性剤、両性イオン界面活性剤、ノニオン性界面活性剤等の界面活性剤を挙げることができる。これらの分散安定補助剤は、１種または２種以上を併用してもよく、得られる熱膨張性微小球の粒子径と重合時の分散安定性等を考慮して、適宜選択される。
高分子タイプの分散安定補助剤としては、たとえば、ジエタノールアミンと脂肪族ジカルボン酸の縮合生成物、ゼラチン、ポリビニルピロリドン、メチルセルロース、ポリエチレンオキサイド、ポリビニルアルコール等を挙げることができる。
カチオン性界面活性剤としては、たとえば、ラウリルアミンアセテート、ステアリルアミンアセテート等のアルキルアミン類、ラウリルトリメチルアンモニウムクロライド等の四級アンモニウム塩等を挙げることができる。
アニオン性界面活性剤としては、たとえば、オレイン酸ナトリウム、ヒマシ油カリ等の脂肪酸油；ラウリル硫酸ナトリウム、ラウリル硫酸アンモニウム等のアルキル硫酸エステル塩；ドデシルベンゼンスルホン酸ナトリウム等のアルキルベンゼンスルホン酸塩；アルキルナフタレンスルホン酸塩；アルカンスルホン酸塩；ジアルキルスルホコハク酸塩アルキルリン酸エステル塩；ナフタレンスルホン酸ホルマリン縮合物；ポリオキシエチレンアルキルフェニルエーテル硫酸エステル塩；ポリオキシエチレンアルキル硫酸エステル塩等を挙げることができる。
両性イオン界面活性剤としては、たとえば、アルキルジメチルアミノ酢酸ベタイン、アルキルジヒドロキシエチルアミノ酢酸ベタイン、ラウリルジメチルアミンオキサイド等を挙げることができる。
ノニオン性界面活性剤としては、たとえば、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレン脂肪酸エステル、ソルビタン脂肪酸エステル、ポリオキシソルビタン脂肪酸エステル、ポリオキシエチレンアルキルアミン、グリセリン脂肪酸エステル、オキシエチレンーオキシプロピレンブロックポリマー等を挙げることができる。
分散安定補助剤の配合量は、特に限定されないが、重合性成分１００重量部に対して、好ましくは０．０００１〜５重量部、さらに好ましくは０．０００３〜２重量部である。
水性分散媒は、たとえば、イオン交換水等の水に、水溶性化合物とともに、必要に応じて分散安定剤および／または分散安定補助剤等を配合して調製される。重合時の水性分散媒のｐＨは、水溶性化合物、分散安定剤、分散安定補助剤の種類によって適宜決められる。重合時の水性分散媒は、酸性、中性、アルカリ性のいずれでもよいが、酸性または中性が好ましく、酸性がさらに好ましい。重合時の水性分散媒のｐＨは、通常２〜１３、好ましくは２〜１０、より好ましくは２〜８、さらに好ましくは２〜６．５、特に好ましくは２〜６、最も好ましくは２〜４である。
本発明では、所定粒子径の球状油滴が調製されるように油性混合物を水性分散媒中に乳化分散させる。
油性混合物を乳化分散させる方法としては、たとえば、ホモミキサー（たとえば、特殊機化工業株式会社製）、ホモディスパー（たとえば、特殊機化工業株式会社製）等により攪拌する方法や、スタティックミキサー（たとえば、株式会社ノリタケエンジニアリング社製）等の静止型分散装置を用いる方法、膜乳化法、超音波分散法、マイクロチャネル法等の一般的な分散方法を挙げることができる。
油性混合物を乳化分散させる方法としては、たとえば、日本国特開２０００−１９１８１７号公報に開示された連続式高速回転高剪断型攪拌分散機を使用する方法もあるが、縦型のスリットを有する通液孔を有する円錐状または円錐台状のスクリーンと、その内側にクリアランスを設けて設置した、羽根刃を有する円錐状または円錐台状のローターとを備えたホモジナイザーのローター側より疎水性物質と水性媒体とを供給しつつローターを高速で回転させて、ローターとスクリーンとのクリアランスおよびスクリーンの通液孔を通過させることにより、油性混合物を水性分散媒中に乳化分散させる方法、すなわち、クレアミックス（日本国特開２００４−９５９号公報の第０００５〜００１３段落および図１〜４等参照）を用いる方法が好ましい。
次いで、油性混合物が球状油滴として水性分散媒に分散された分散液を加熱することにより、懸濁重合を開始する。重合反応中は、分散液を攪拌するのが好ましく、その攪拌は、たとえば、単量体の浮上や重合後の熱膨張性微小球の沈降を防止できる程度に緩く行えばよい。
重合温度は、重合開始剤の種類によって自由に設定されるが、好ましくは３０〜１００℃、さらに好ましくは４０〜９０℃、特に好ましくは５０〜８５℃の範囲で制御される。反応温度を保持する時間は、０．１〜２０時間程度が好ましい。重合初期圧力については特に限定はないが、ゲージ圧で０〜５．０ＭＰａ、さらに好ましくは０．１〜３．０ＭＰａ、特に好ましくは０．２〜２．０ＭＰａの範囲である。
重合反応終了後、所望により、分散安定剤を塩酸等により分解し、得られた生成物（熱膨張性微小球）を吸引濾過、遠心分離、遠心濾過等の操作により、分散液から単離する。さらに、得られた熱膨張性微小球の含水ケーキを水洗し、乾燥して熱膨張性微小球を得ることができる。
本発明の熱膨張性微小球の製造方法は、微粒子充填剤を外殻の外表面に付着させる工程をさらに含むことがある。熱膨張性微小球において、その外殻の外表面に微粒子充填剤が付着していると、使用時における分散性の向上や流動性改善が図られる。
微粒子充填剤は、有機系および無機系充填剤のいずれでもよく、その種類および量は、使用目的に応じて適宜選定される。
有機系充填剤としては、たとえば、ステアリン酸マグネシウム、ステアリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸バリウム、ステアリン酸リチウム等の金属セッケン類；ポリエチレンワックス、ラウリン酸アミド、ミリスチン酸アミド、パルミチン酸アミド、ステアリン酸アミド、硬化ひまし油等の合成ワックス類；ポリアクリルアミド、ポリイミド、ナイロン、ポリメタクリル酸メチル、ポリエチレン、ポリテトラフルオロエチレン等の樹脂粉体等が挙げられる。
無機系充填剤としては、層状構造を有するもの、たとえば、タルク、マイカ、ベントナイト、セリサイト、カーボンブラック、二硫化モリブデン、二硫化タングステン、弗化黒鉛、弗化カルシウム、窒化ホウ素等；その他、シリカ、アルミナ、雲母、炭酸カルシウム、水酸化カルシウム、リン酸カルシウム、水酸化マグネシウム、リン酸マグネシウム、硫酸バリウム、二酸化チタン、酸化亜鉛、セラミックビーズ、ガラスビーズ、水晶ビーズ等が挙げられる。
これらの微粒子充填剤は、１種または２種以上を併用してもよい。
微粒子充填剤の平均粒子径は、付着前の熱膨張性微小球の平均粒子径の１／１０以下であることが好ましい。ここで、平均粒子径とは、一次粒子における平均粒子径を意味する。
熱膨張性微小球への微粒子充填剤の付着量は、特に限定はないが、微粒子充填剤による機能を十分に発揮でき、熱膨張性微小球の真比重の大きさ等を考慮すると、付着前の熱膨張性微小球１００重量部に対して、好ましくは０．１〜９５重量部、さらに好ましくは０．５〜６０重量部、特に好ましくは５〜５０重量部、最も好ましくは８〜３０重量部である。
微粒子充填剤の付着は、付着前の熱膨張性微小球と微粒子充填剤とを混合することによって行うことができる。混合については、特に限定はなく、容器と攪拌羽根といった極めて簡単な機構を備えた装置を用いて行うことができる。また、一般的な揺動または攪拌を行える粉体混合機を用いてもよい。粉体混合機としては、たとえば、リボン型混合機、垂直スクリュー型混合機等の揺動攪拌または攪拌を行える粉体混合機を挙げることができる。また、近年、攪拌装置を組み合わせたことにより効率のよい多機能な粉体混合機であるスーパーミキサー（株式会社カワタ製）およびハイスピードミキサー（株式会社深江製）、ニューグラマシン（株式会社セイシン企業製）、ＳＶミキサー（株式会社神鋼環境ソリューション社製）等を用いてもよい。
本発明の製造方法は、水溶性化合物として水溶性金属塩（水和物）を使用する場合、発明の見方をかえると、熱可塑性樹脂からなる外殻と、それに内包され且つ前記熱可塑性樹脂の軟化点以下の沸点を有する発泡剤とから構成される熱膨張性微小球の製造方法であって、スカンジウム、セリウム、チタン、ジルコニウム、ハフニウム、バナジウム、タンタル、クロム、モリブデン、タングステン、マンガン、レニウム、鉄、ルテニウム、オスミウム、コバルト、ロジウム、ニッケル、銀、金、亜鉛、カドミウム、ホウ素、アルミニウム、ガリウム、インジウム、タリウム、スズ、鉛、ヒ素、アンチモンおよびビスマスから選ばれた少なくとも一種の金属のイオン０．００１〜１００ｐｐｍおよびハロゲンイオン０．００１ｐｐｍ以上を含有する水性分散媒中に、重合性成分と前記発泡剤とを含有する油性混合物を分散させ、前記油性混合物に含まれる前記重合性成分を重合させる工程を含む製造方法でもある。
上記「少なくとも一種の金属」を、以下では金属Ａということがある。また、この製造方法を、以下では製造方法Ａということもある。金属Ａイオンは、水溶性金属塩（水和物）から由来する金属イオンであると好ましく、金属ハロゲン化物および／またはその水和物から由来する金属イオンであるとさらに好ましい。なお、製造方法Ａに関して以下に説明する内容以外については、上述の製造方法の説明をそのまま当てはめることができる。
水性分散媒中に含有される金属Ａイオンの量は、好ましくは０．００１〜５０ｐｐｍ、さらに好ましくは０．００１〜１０ｐｐｍ、特に好ましくは０．０１〜１０ｐｐｍである。金属Ａイオンの量が少なすぎると、本発明で得られる効果が得られないことがある。一方、金属Ａイオンの量が多すぎると、重合速度が低下したり、原料である重合性成分の残存量が増加ということがある。また、水性分散媒中に含有されるハロゲンイオンの量は、好ましくは０．０１ｐｐｍ以上、さらに好ましくは０．１ｐｐｍ以上、特に好ましくは１ｐｐｍ以上である。ハロゲンイオンの量が少ないと、本発明で得られる効果が得られないことがある。
金属Ａイオン０．００１〜１００ｐｐｍおよびハロゲンイオン０．００１ｐｐｍ以上を含有する水性分散媒中で重合性成分を重合することによって、膨張倍率が高く、熱膨張させた場合に優れた繰り返し圧縮耐久性を有する中空微粒子となる熱膨張性微小球を、効率よく製造することができる。また、製造方法Ａでは、重合時における生成粒子の凝集や重合反応器内のスケール発生を防止することもできる。
なお、水性分散媒が、塩化リチウム、塩化ナトリウム、塩化カリウム、塩化マグネシウム、塩化カルシウム等のハロゲンイオンを含む電解質を含有しない場合は、ハロゲンイオンの量は、好ましくは０．００１〜５０ｐｐｍ、さらに好ましくは０．００１〜１０ｐｐｍ、特に好ましくは０．０１〜１０ｐｐｍである。
〔熱膨張性微小球およびその用途〕
本発明の熱膨張性微小球は、図１に示すように、熱可塑性樹脂からなる外殻（シェル）１１とそれに内包され且つ前記熱可塑性樹脂の軟化点以下で気化する発泡剤（コア）１２とから構成されたコア−シェル構造をとっており、熱膨張性微小球は微小球全体として熱膨張性（微小球全体が加熱により膨らむ性質）を示す。熱可塑性樹脂、重合して熱可塑性樹脂となる重合性成分、発泡剤等については、前述のとおりである。
本発明の熱膨張性微小球の最大膨張時の膨張倍率は、５０倍以上であり、好ましくは５５倍以上、より好ましくは６０倍以上、さらに好ましくは６５倍以上、特に好ましくは７０倍以上、最も好ましくは７５倍以上である。熱膨張性微小球の最大膨張時の膨張倍率が５０倍未満であると、熱膨張性微小球の熱膨張性が低く、熱膨張時の体積増加が十分ではなく、さらに内包保持性能や耐溶剤性能が低くなる可能性があり好ましくない。
膨張倍率は、一般に熱膨張性微小球の最も基本的な物性であり、熱膨張性微小球を熱膨張させて得られる中空微粒子について、軽量化や体積増加を目的にする場合に不可欠な物性である。膨張倍率には、種々定義があるが、最大膨張時の膨張倍率は、最大膨張を示したときの中空微粒子の真比重を膨張前の熱膨張性微小球の真比重で除することによって計算される百分率と定義する。
最大膨張時の膨張倍率が高いということは、一般に熱膨張性微小球は膨張に伴い熱膨張性微小球の外殻の厚みが薄くなるが、薄くなった状態であっても外殻の内側に封入されている発泡剤を漏れることなく保持できることを意味している。すなわち、熱膨張性微小球の物性において最大膨張時の膨張倍率が高いということは、発泡剤保持性能が高く、良好な外殻が形成されていることと同義である。また、良好な外殻が形成された熱膨張性微小球では、各種溶剤にさらされても熱膨張性能を損なわず、耐溶剤性が高いことも知られている。したがって、最大膨張時の膨張倍率の評価は、熱膨張性微小球の物性評価において非常に重要な評価項目である。
本発明の熱膨張性微小球は、これを熱膨張させて得られる中空微粒子の繰り返し圧縮耐久性が７５％以上であり、好ましくは７８％以上、より好ましくは８０％以上、さらに好ましくは８３％以上、特に好ましくは８５％以下、最も好ましくは８８％以上である。中空微粒子の繰り返し圧縮耐久性が７５％未満であると、この熱膨張性微小球を原料として得られる成形品や塗膜等の成形物について、軽量性、多孔性、吸音性、断熱性、熱伝導性、意匠性、強度等の諸物性が低下したり、内包保持性能や耐溶剤性能が低くなる。
繰り返し圧縮耐久性は、熱膨張性微小球を熱膨張させて得られ、真比重が（０．０２５±０．００１）ｇ／ｃｃの中空微粒子について、実施例で詳しく説明する測定方法に従って、測定される。なお、繰り返し圧縮耐久性を測定するために熱膨張性微小球を熱膨張させて中空微粒子を得る方法は、実施例に示すように、後述の乾式加熱膨張法の一種である内部噴射方法が採用される。内部噴射方法が採用される理由としては、得られる中空微粒子が乾燥した状態であるので、湿式加熱膨張法のように中空微粒子を乾燥させる工程が不要である点や、得られる中空微粒子の分散性が優れている点が挙げられる。
膨張前の熱膨張性微小球の真比重は、一般に、約１ｇ／ｃｃである。本発明の熱膨張性微小球では、最大膨張時の膨張倍率が５０倍以上であるので、最大膨張時では得られる中空微粒子の真比重が約０．０２ｇ／ｃｃ以下となる。実際のところ、中空微粒子の真比重が約０．０２ｇ／ｃｃでは、繰り返し圧縮耐久性を評価しても優劣の判断が分かりにくいことがある。それに対して、最大膨張とならない可能性が高い、真比重が（０．０２５±０．００１）ｇ／ｃｃである中空微粒子では、膨張の程度が若干抑えられており、繰り返し圧縮耐久性の評価が行いやすく、優劣の差が明確となる。このような事情から、真比重（０．０２５±０．００１）ｇ／ｃｃである中空微粒子について、繰り返し圧縮耐久性が測定される。
繰り返し圧縮耐久性は、後述の基材成分と中空微粒子とを混合した際や、基材成分と中空微粒子とからなる組成物を成形する際に生じる応力に対する中空微粒子の耐久性を評価する物性値である。中空微粒子の繰り返し圧縮耐久性を評価するということは、中空微粒子の外殻の繰り返し屈曲に対する耐久性を評価することと同義であるといえる。中空微粒子の外殻が繰り返し屈曲に対して高い耐久性を有するということは、中空微粒子の外殻が繰り返し屈曲時に部分的に腑弱することなく材質的に均一な熱可塑性樹脂で形成されていることを意味している。中空微粒子の外殻が材質的に均一であるということは、まさに中空微粒子の原料である熱膨張性微小球においても材質的に均一で良好な外殻が形成されているということと同義である。また、材質的に均一で良好な外殻が形成された熱膨張性微小球は、各種溶剤にさらされても熱膨張性能を損なわず、耐溶剤性が高いということもわかっている。逆に、外殻が材質的に不均一で弱い部分があると、その部分から発泡剤の吹き抜けが起こったり、各種溶剤にさらされた場合はその部分から膨潤されたりして熱膨張性能を損なうことがある。
上記のように、繰り返し圧縮耐久性が高い中空微粒子および／またはその原料である熱膨張性微小球を基材成分と混合した際や、基材成分と中空微粒子および／または熱膨張性微小球とからなる組成物を成形や塗工する際に、生じる応力に対する耐久性が高くなり、応力を受けることによる破損が生じにくい。
熱膨張性微小球は、以下の諸物性をさらに有すると好ましい。
熱膨張性微小球の平均粒子径については、用途に応じて自由に設計することができるために特に限定されないが、通常１〜１００μｍ、好ましくは２〜８０μｍ、さらに好ましくは３〜６０μｍ、特に好ましくは５〜５０μｍ以上である。
熱膨張性微小球の粒度分布の変動係数ＣＶは、特に限定されないが、好ましくは３５％以下、さらに好ましくは３０％以下、特に好ましくは２５％以下である。変動係数ＣＶは、以下に示す計算式（１）および（２）で算出される。
ＣＶ＝（ｓ／＜ｘ＞）×１００（％） ・・・（１）

（式中、ｓは粒子径の標準偏差、＜ｘ＞は平均粒子径、ｘ_ｉはｉ番目の粒子径、ｎは粒子の数である。）
熱膨張性微小球に封入された発泡剤の内包率については、用途に応じて自由に設計することができるために特に限定されないが、熱膨張性微小球の重量に対して、好ましくは２〜６０重量％、さらに好ましくは５〜５０重量％、特に好ましくは８〜４５重量％である。
本発明の熱膨張性微小球は、上記で説明した製造方法によって製造することができるが、この製造方法に限定されない。本発明の熱膨張性微小球は、たとえば、界面重合法、逆相乳化法、乳化重合法等で製造することも可能であると考えられる。また、水性分散媒中で液滴を作製しない方法として、たとえば、液中乾燥法、コアセルベーション法、噴霧乾燥法、乾式混合法等で製造することも可能であると考えられる。また、本発明とは別の製造方法で得られた熱膨張性微小球の外殻にポリマーをグラフト重合させて製造することも可能であると考えられる。
本発明の熱膨張性微小球および／または本発明の製造方法で得られた熱膨張性微小球を加熱膨張させることによって、熱膨張した微小球（中空微粒子）を製造できる。中空微粒子の製造方法については、特に限定はなく、乾式加熱膨張法、湿式加熱膨張法のいずれでもよい。
乾式加熱膨張法としては、日本国特開２００６−２１３９３０号公報に記載されている内部噴射方法を挙げることができる。この内部噴射方法は、熱膨張性微小球を含む気体流体を、出口に分散ノズルを備え且つ熱風流の内側に設置された気体導入管に流し、前記分散ノズルから噴射させる工程（噴射工程）と、前記気体流体を前記分散ノズルの下流部に設置された衝突板に衝突させ、熱膨張性微小球を前記熱風流中に分散させる工程（分散工程）と、分散した熱膨張性微小球を前記熱風流中で膨張開始温度以上に加熱して膨張させる工程（膨張工程）とを含む乾式加熱膨張法である。内部噴射方法では、原料となる熱膨張性微小球の外殻を構成する熱可塑性樹脂の種類にかかわらず均一物性の中空微粒子を得ることができるので好ましい。内部噴射方法の詳細は実施例に記載する。
また、別の乾式加熱膨張法としては、日本国特開２００６−９６９６３号公報に記載の方法等がある。湿式加熱膨張法としては、日本国特開昭６２−２０１２３１号公報に記載の方法等がある。
中空微粒子の平均粒子径については、用途に応じて自由に設計することができるために特に限定はないが、好ましくは１〜１０００μｍ、さらに好ましくは５〜８００μｍ、特に好ましくは１０〜５００μｍである。また、中空微粒子の粒度分布の変動係数ＣＶについても、特に限定はないが、３０％以下が好ましく、さらに好ましくは２７％以下、特に好ましくは２５％以下である。
本発明の組成物は、基材成分と、熱膨張性微小球および／また中空微粒子とを含む。
基材成分としては特に限定はないが、たとえば、天然ゴムやブチルゴムやシリコンゴム等のゴム類；エポキシ樹脂やフェノール樹脂等の熱硬化性樹脂；変性シリコン系、ウレタン系、ポリサルファイド系、アクリル系、シリコン系等のシーリング材料；エチレン−酢酸ビニル共重合物系、塩化ビニル系やアクリル系の塗料成分；セメントやモルタルやコージエライト等の無機物等が挙げられる。本発明の組成物は、これらの基材成分と熱膨張性微小球および／また中空微粒子とを混合することによって調製することができる。
本発明の組成物の用途としては、たとえば、成形用組成物、塗料組成物、粘土組成物、繊維組成物、接着剤組成物、粉体組成物等を挙げることができる。
本発明の成形物は、この組成物を成形して得られる。本発明の成形物としては、たとえば、成形品や塗膜等の成形物等を挙げることができる。本発明の成形物では、軽量性、多孔性、吸音性、断熱性／熱伝導性、電気伝導度、意匠性、衝撃吸収性、強度等の諸物性が向上している。   Hereinafter, the present invention will be described in detail.
[Method for producing thermally expandable microspheres]
  The production method of the present invention is a method for producing thermally expandable microspheres composed of an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and having a boiling point equal to or lower than the softening point of the thermoplastic resin. In the production method of the present invention, an oily mixture containing a polymerizable component and the foaming agent is dispersed in an aqueous dispersion medium containing a specific water-soluble compound, and the polymerizable component contained in the oily mixture is polymerized. Process.
  The blowing agent is not particularly limited as long as it is a substance having a boiling point equal to or lower than the softening point of the thermoplastic resin. For example, hydrocarbons having 1 to 12 carbon atoms and their halides; having an ether structure, chlorine atoms and Examples thereof include a fluorine-containing compound having 2 to 10 carbon atoms that does not contain a bromine atom; tetraalkylsilane; a compound that thermally decomposes by heating to generate a gas, and one or more of them may be used in combination. .
  Examples of the hydrocarbon having 1 to 12 carbon atoms include propane, cyclopropane, propylene, butane, normal butane, isobutane, cyclobutane, normal pentane, cyclopentane, isopentane, neopentane, normal hexane, isohexane, cyclohexane, heptane, cycloheptane. , Hydrocarbons such as octane, isooctane, cyclooctane, 2-methylpentane, 2,2-dimethylbutane, and petroleum ether. These hydrocarbons may be linear, branched or alicyclic, and are preferably aliphatic.
  Examples of the hydrocarbon halide having 1 to 12 carbon atoms include methyl chloride, methylene chloride, chloroform and carbon tetrachloride.
  Examples of the fluorine-containing compound having an ether structure and not containing a chlorine atom and a bromine atom and having 2 to 10 carbon atoms include, for example, C₃H₂F₇OCF₂H, C₃HF₆OCH₃, C₂HF₄OC₂H₂F₃, C₂H₂F₃OC₂H₂F₃, C₄HF₈OCH₃, C₃H₂F₅OC₂H₃F₂, C₃HF₆OC₂H₂F₃, C₃H₃F₄OCHF₂, C₃HF₆OC₃H₂F₅, C₄H₃F₆OCHF₂, C₃H₃F₄OC₂HF₄, C₃HF₆OC₃H₃F₄, C₃F₇OCH₃, C₄F₉OCH₃, C₄F₉OC₂H₅, C₇F₁₅OC₂H₅And the like. These fluorine-containing compounds may be used alone or in combination of two or more. The (fluoro) alkyl group of the hydrofluoroether may be linear or branched.
  Examples of the tetraalkylsilane include silanes having an alkyl group having 1 to 5 carbon atoms, such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane. .
  Examples of the compound that generates a gas upon thermal decomposition by heating include azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, 4,4′-oxybis (benzenesulfonylhydrazide), and the like.
  The polymerizable component is a component that becomes a thermoplastic resin that forms the outer shell of the thermally expandable microsphere by polymerization in the presence of a polymerization initiator. The polymerizable component is a component which essentially includes a monomer component and may contain a crosslinking agent.
  The monomer component generally includes a component called a (radical) polymerizable monomer having one polymerizable double bond, and is not particularly limited. For example, acrylonitrile, methacrylonitrile, α -Nitrile monomers such as chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid; vinyl chloride, vinylidene chloride, Vinyl halide monomers such as vinyl bromide and vinyl fluoride; vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl butyrate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (Meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pro Pyr (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, 2-chloroethyl (meth) acrylate, phenyl (meth) acrylate, isobornyl ( (Meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, β-carboxyethyl acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, etc. Body; styrene monomer such as styrene, α-methylstyrene, chlorostyrene; acrylamide monomer such as acrylamide, substituted acrylamide, methacrylamide, substituted methacrylamide; N-phenyl Maleimide monomers such as maleimide, N- (2-chlorophenyl) maleimide, N-cyclohexylmaleimide, N-laurylmaleimide; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn octylstyrene, pn-nonylstyrene, pn-decylstyrene, p- Styrene monomers such as n-dodecyl styrene, n-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichlorostyrene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene Monomer: Vinyl methyl ether, vinyl ethyl ether, vinyl Vinyl ether monomers such as sobutyl ether; Vinyl ketone monomers such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. N-vinyl monomers, vinyl naphthalene salts and the like. As for the carboxyl group-containing monomer, some or all of the carboxyl groups may be neutralized during polymerization. In addition, (meth) acryl means acryl or methacryl. The maleimide monomer is preferably an N-substituted maleimide monomer having a structure having a substituent on a nitrogen atom.
  These radical polymerizable monomers constituting the polymerizable component may be used alone or in combination of two or more. Among these, the polymerizable components are nitrile monomers, (meth) acrylate monomers, carboxyl group-containing monomers, styrene monomers, vinyl acetate, acrylamide monomers, maleimides. It is preferable that at least one selected from a monomer and a vinyl halide monomer is included.
  When the polymerizable component contains a nitrile monomer as an essential component, it is preferable because the heat resistance and solvent resistance of the thermoplastic resin constituting the outer shell of the thermally expandable microsphere are improved.
  Further, it is preferable that the polymerizable component further contains a vinyl halide monomer and / or a (meth) acrylic acid ester monomer together with the nitrile monomer. When a halogenated vinyl monomer such as vinylidene chloride is included, gas barrier properties are improved. When the polymerizable component contains a (meth) acrylic acid ester monomer, the expansion behavior can be easily controlled.
  When the polymerizable component further contains a carboxyl group-containing monomer together with the nitrile monomer, the heat resistance and solvent resistance are improved, the glass transition temperature of the thermoplastic resin is increased, and the thermally expandable microspheres are heated to a high temperature. It is preferable because it can be thermally expanded. The polymerizable component may further contain a vinyl halide monomer and / or a (meth) acrylate monomer together with the nitrile monomer and the carboxyl group-containing monomer.
  In the above, when the polymerizable component further contains a maleimide monomer, it is preferable because the heat-expandable microspheres are less colored.
  Although there is no limitation in particular about the ratio of each radically polymerizable monomer which comprises a polymeric component, in the following (A)-(F), the weight ratio shown below is preferable.
(A) When the polymerizable component contains a halogenated vinyl monomer as an essential component
  The weight ratio of the vinyl halide monomer is preferably 10% by weight or more, more preferably 20% by weight or more, particularly preferably 30% by weight or more, based on the monomer component. Preferably it is 40 weight% or more.
(B) When the polymerizable component contains a nitrile monomer and a (meth) acrylic acid ester monomer as essential components together with a vinyl halide monomer
  The weight ratio of the vinyl halide monomer is preferably 90 to 10% by weight, more preferably 85 to 15% by weight, still more preferably 80 to 20% by weight, based on the monomer component. Especially preferably, it is 75-25 weight%, Most preferably, it is 70-40 weight%. The weight ratio of the nitrile monomer is preferably 10 to 90% by weight, more preferably 15 to 85% by weight, still more preferably 20 to 80% by weight, particularly preferably based on the monomer component. Is 25 to 70% by weight, most preferably 30 to 60% by weight. The weight ratio of the (meth) acrylic acid ester monomer is preferably 1 to 20% by weight, more preferably 3 to 18% by weight, most preferably 5 to 15% by weight, based on the monomer component. It is.
(C) When the polymerizable component contains a (meth) acrylate monomer as an essential component together with a nitrile monomer
  The weight ratio of the nitrile monomer is preferably 30 to 99% by weight, more preferably 35 to 99% by weight, still more preferably 40 to 99% by weight, particularly preferably based on the monomer component. Is 45-99 wt%, most preferably 50-99 wt%. The weight ratio of the (meth) acrylic acid ester monomer is preferably 70 to 1% by weight, more preferably 65 to 1% by weight, still more preferably 60 to 1% by weight, based on the monomer component. And particularly preferably 55 to 1% by weight, most preferably 50 to 1% by weight.
(D) When the polymerizable component contains a maleimide monomer as an essential component
  The weight ratio of the maleimide monomer is preferably from 0.1 to 60% by weight, more preferably from 0.3 to 55% by weight, particularly preferably 0.5%, based on the monomer component. -50% by weight or more, most preferably 1-50% by weight or more.
(E) When the polymerizable component contains a carboxyl group-containing monomer as an essential component
  The weight ratio of the carboxyl group-containing monomer is preferably 5% by weight or more, more preferably 10% by weight or more, particularly preferably 15% by weight or more, and most preferably based on the monomer component. Is 20% by weight or more.
(F) The polymerizable component contains a nitrile monomer and a carboxyl group-containing monomer as an essential component
  The weight ratio of the nitrile monomer is preferably 20 to 95% by weight, more preferably 20 to 90% by weight, still more preferably 20 to 85% by weight, particularly preferably based on the monomer component. Is 20 to 80% by weight, most preferably 20 to 60% by weight. The weight ratio of the carboxyl group-containing monomer is preferably 5 to 80% by weight, more preferably 10 to 80% by weight, and still more preferably 15 to 80% by weight with respect to the monomer component. Preferably it is 20-80 weight%, Most preferably, it is 40-80 weight%.
  When the monomer component contains a carboxyl group-containing monomer as an essential component (that is, in the case of (E) and (F) above), a monomer other than the carboxyl group-containing monomer contained in the monomer component As above, a monomer that reacts with the carboxyl group of the carboxyl group-containing monomer may be contained. When the monomer component includes a monomer that reacts with the carboxyl group of the carboxyl group-containing monomer together with the carboxyl group-containing monomer, the heat resistance is further improved, and the expansion performance at high temperatures is improved.
  Examples of the monomer that reacts with the carboxyl group of the carboxyl group-containing monomer include, for example, N-methylol (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth). Acrylate, magnesium mono (meth) acrylate, zinc mono (meth) acrylate, vinyl glycidyl ether, propenyl glycidyl ether, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Examples thereof include butyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate. The weight ratio of the monomer that reacts with the carboxyl group of the carboxyl group-containing monomer is preferably 0.1 to 10% by weight, more preferably 1 to 8% by weight, based on the monomer component. Most preferably, it is 3 to 5% by weight.
  When the monomer component contains a monomer having halogen, oxygen, nitrogen, etc., it is possible to effectively prevent aggregation of thermally expandable microspheres generated during polymerization and generation of scale in the polymerization reactor. it can.
  The polymerizable component may contain a polymerizable monomer (crosslinking agent) having two or more polymerizable double bonds in addition to the monomer component. By polymerizing using a crosslinking agent, a decrease in the retention rate (encapsulation retention rate) of the encapsulated foaming agent after thermal expansion is suppressed, and thermal expansion can be effectively performed.
  The crosslinking agent is not particularly limited. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) Acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, PEG # 200 Di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol dimethacrylate, 1,6-hexanedi Di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimethylolpropane trimethacrylate, glycerin dimethacrylate, dimethylol-tricyclodecane diacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetraacrylate, di Pentaerythritol hexaacrylate, neopentyl glycol acrylic acid benzoate, trimethylolpropane acrylic acid benzoate, 2-hydroxy-3-acryloyloxypropyl methacrylate, hydroxypivalate neopentyl glycol diacrylate, ditrimethylolpropane tetraacrylate, Di (meth) acrylate such as 2-butyl-2-ethyl-1,3-propanediol diacrylate Mention may be made of the door compound. These crosslinking agents may be used alone or in combination of two or more. In the above, a series of compounds described as “PEG # XX (di) methacrylate” is polyethylene glycol di (meth) acrylate, which means that the average molecular weight of the polyethylene glycol moiety is XXX. To do.
  The amount of the cross-linking agent is not particularly limited, but considering the degree of cross-linking, the retention rate of the foaming agent encapsulated in the outer shell, heat resistance and thermal expansion, the amount is 100 parts by weight of the monomer component. When the amount of the crosslinking agent is in the range of 1) to 7) shown below, it is more preferable in this order (a range described after the range described before is preferable).
1) 0.01-5 parts by weight, 2) 0.03-3 parts by weight, 3) 0.05-3 parts by weight, 4) 0.05-2.5 parts by weight, 5) 0.1-2. 5 parts by weight, 6) 0.1 to 2 parts by weight, and 7) 0.3 to 2 parts by weight.
  In the production method of the present invention, it is preferable to polymerize a polymerizable component in the presence of a polymerization initiator using an oily mixture containing a polymerization initiator.
  The polymerization initiator is not particularly limited, and examples thereof include peroxides such as peroxydicarbonate, peroxyester, and diacyl peroxide; azo compounds and the like. These polymerization initiators may be used alone or in combination of two or more. The polymerization initiator is preferably an oil-soluble polymerization initiator that is soluble in the radical polymerizable monomer.
  Examples of peroxydicarbonate include diethyl peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, and di-2-ethoxy. Ethyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-octyl peroxydicarbonate, dicyclohexyl peroxy Examples thereof include dicarbonate and dibenzyl peroxydicarbonate.
  Examples of peroxyesters include t-butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, and 2,5-dimethyl-2. , 5-bis (2-ethylhexanoylperoxy) hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypi Valate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxy Neodecanoate, cumylperoxyneodecanoate and t-butylperoxy3,5,5-trime And the like can be given Ruhekisanoeto.
  Examples of the diacyl peroxide include peroxides such as octanoyl peroxide, lauroyl peroxide, stearyl peroxide, succinic acid peroxide, and benzoyl peroxide; 2,2′-azobis (4-methoxy-2,4 -Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionate), 2 , 2'-azobis (2-methylbutyronitrile) and the like.
  Among these polymerization initiators, peroxydicarbonate is preferred, the formation of resin particles inside the thermally expandable microspheres is suppressed, and the thickness of the outer shell is less likely to be less than the theoretical value, resulting in the heat obtained. The expansion magnification of the expandable microsphere is increased. In view of the availability of peroxydicarbonate, (co) polymerization of the polymerizable component, randomization of the thermoplastic resin structure constituting the outer shell, etc., diisopropyl peroxydicarbonate, bis (4 -T-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate and at least one selected from the group consisting of di-2-ethylhexylperoxydicarbonate is more preferred, and di-sec-butylperoxy Particularly preferred is at least one selected from dicarbonate and di-2-ethylhexyl peroxydicarbonate.
  The amount of the polymerization initiator is not particularly limited, but is preferably 0.3 to 8 parts by weight, more preferably 0.4 to 7.5 parts by weight, based on 100 parts by weight of the monomer component. Furthermore, it is 0.5 to 7.5 parts by weight, particularly preferably 0.5 to 7 parts by weight, and most preferably 0.8 to 7 parts by weight.
  When the polymerization initiator contains other initiators together with peroxydicarbonate, the effect obtained is higher as the proportion of peroxydicarbonate in the polymerization initiator increases. The proportion of peroxydicarbonate in the polymerization initiator is preferably 60% by weight or more, more preferably 70% by weight or more, further preferably 80% by weight or more, particularly preferably 90% by weight or more, and most preferably 100% by weight. .
  In the production method of the present invention, the oily mixture may further contain a chain transfer agent, an organic pigment, an inorganic pigment or an inorganic particle whose surface is subjected to hydrophobic treatment, and the like.
  The chain transfer agent is not particularly limited, and examples thereof include mercaptan, indene, α-methylstyrene dimer, terpinolene and the like.
  The organic pigment is not particularly limited. For example, aluminum lake such as tartrazine, sunset erotic FCF, brilliant blue FCF, zirconium lake, barium lake, herringdon pink CN, risol rubin BCA, lake CBA, phthalocyanine blue, permanent orange Etc.
  There are no particular limitations on the inorganic pigment or inorganic particle whose surface has been subjected to hydrophobic treatment. For example, titanium oxide, zinc oxide, zirconium oxide, magnesium oxide, iron oxide, cerium oxide, iron hydroxide, chromium oxide, and hydroxide Chromium, ultramarine, bitumen, manganese violet, ultraviolet, titanium black, carbon black, aluminum powder, titanium mica, bismuth oxychloride, titanium oxide-treated mica titanium, bituminized mica titanium, carmine-treated mica titanium, silica, calcium carbide, carbonic acid Examples include magnesium, barium sulfate, barium silicate, calcium silicate, magnesium silicate, calcium phosphate, hydroxyapatite, zeolite, alumina, talc, mica, bentonite, kaolin, sericite, and the like subjected to surface hydrophobic treatment. The surface hydrophobic treatment of the inorganic pigment or inorganic particle is not particularly limited, and examples thereof include a method of wetting using silicon oil and the like, a surface treatment method using a silane coupling agent, and the like.
  In the present invention, the aqueous dispersion medium is a medium mainly composed of ion-exchanged water in which the oily mixture is dispersed, and may further contain a hydrophilic organic solvent such as alcohol. Although there is no limitation in particular about the usage-amount of an aqueous dispersion medium, it is preferable to use 100-1000 weight part aqueous dispersion medium with respect to 100 weight part of polymeric components.
  The aqueous dispersion medium may further contain an electrolyte. The electrolyte is not particularly limited. For example, lithium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium hydrogen carbonate, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, ammonium sulfate, sodium carbonate, benzoic acid, etc. Can be mentioned. These electrolytes may be used alone or in combination of two or more. Although there is no limitation in particular about content of an electrolyte, it is preferable to contain 0.1-50 weight part with respect to 100 weight part of aqueous dispersion media.
  In the production method of the present invention, the aqueous dispersion medium contains at least one water-soluble compound. The water-soluble compound is a component used as a so-called polymerization aid in the method for producing thermally expandable microspheres. In addition, the water solubility in this invention means the state which melt | dissolves 1g or more per 100g of water. Examples of water-soluble compounds include the following water-soluble compounds (1) to (4). These water-soluble compounds may be used alone or in combination of two or more. Hereinafter, the water-soluble compound will be described in detail.
Water-soluble compound (1): Water-soluble metal salt and / or hydrate thereof (hereinafter referred to as “water-soluble metal salt and / or hydrate thereof” is simply referred to as “water-soluble metal salt (hydrate) ) ".
  The water-soluble metal salt is a metal salt having a property soluble in water.
  Examples of the metal constituting the water-soluble metal salt include group 3 metals such as scandium and cerium; group 4 metals such as titanium, zirconium and hafnium; group 5 metals such as vanadium and tantalum; 6 such as chromium, molybdenum and tungsten. Group 7 metals such as manganese and rhenium; Group 8 metals such as iron, ruthenium and osmium; Group 9 metals such as cobalt and rhodium; Group 10 metals such as nickel; Group 11 metals such as silver and gold; Group 12 metals such as cadmium; Group 13 metals such as boron, aluminum, gallium, indium, and thallium; Group 14 metals such as tin and lead; Group 15 metals such as arsenic, antimony, and bismuth. Among these metals, titanium, iron, aluminum, antimony, and bismuth are preferable, aluminum, iron, and antimony are more preferable, and antimony and aluminum are particularly preferable. The classification of the above metals is at the end of “Chemistry and Education”, Volume 54, No. 4 (2006), published by the Chemical Society of Japan.

Based on.
  The valence of the metal is not particularly limited, but it is 3 out of various valences in that the effects of the present invention are sufficiently obtained and the activity is not too strong and not too weak. Is preferred. Although its action and mechanism are not necessarily clear, the trivalent metal is not directly involved in the radical polymerization mechanism of the oily polymerizable component, but acts as an electron acceptor dissolved in water and is suspended during polymerization. It accepts electrons at the surface of the drop. As a result, the polymerization of the oily mixture is promoted, and the accepted electrons are released into the aqueous system and are considered to be involved in the polymerization reaction.
  The water-soluble metal salt is not particularly limited, and examples thereof include metal halides, which may further contain an organic group in the molecule. The halogen constituting the metal halide is not particularly limited, but can include at least one selected from fluorine, chlorine, bromine, iodine and astatine, and preferably at least one selected from fluorine, chlorine and bromine. , Chlorine and / or bromine are more preferable, and chlorine is particularly preferable.
  Examples of the organic group that may be contained in the metal halide molecule include, for example, alkyl groups, aryl groups, hydroxyl groups, alkoxy groups, acyloxy groups, amino groups, nitro groups, cyano groups, phenyl groups, phenoxy groups, Tolyl group, benzyl group, carboxy group, thiocarboxy group, thiocarbonyl group, thionyl group, thioacetyl group, mercapto group, sulfo group, sulfino group, mesyl group, tosyl group, triflate group, trifurylimide group, acetylacetonate group Etc.
  The metal halide is preferably a trivalent metal halide (metal (III) halide). Specific examples of the metal (III) halide include, for example, aluminum (III) chloride, antimony (III) chloride, gallium (III) chloride, gold (III) chloride, cerium (III) chloride, thallium (III) chloride, Tungsten chloride (III), tantalum chloride (III), titanium chloride (III), iron chloride (III) nickel chloride (III), vanadium chloride (III) bismuth chloride (III), arsenic chloride (III), ruthenium chloride ( III), metal chlorides such as rhenium chloride (III), osmium chloride (III); metal fluorides such as aluminum fluoride (III) and manganese fluoride (III); aluminum bromide (III), bromide Examples thereof include metal bromides such as thallium (III). These metal halides may be used alone or in combination of two or more.
  Some water-soluble metal salts, such as anhydrous aluminum chloride, easily react with water to generate hydrogen chloride, and depending on conditions such as pH, water-insoluble hydroxides are generated. In such a case, since the concentration of aluminum (III) dissolved in water becomes unclear and hydrogen chloride corrodes the metal reactor, water-soluble metal salt hydrates are preferable.
  The water-soluble metal salt hydrate has a complex structure in which water is coordinated around the metal element of the water-soluble metal salt. Although there is no limitation in particular as a hydrate of a water-soluble metal salt, The hydrate of the metal halide demonstrated above can be mentioned. These water-soluble metal salt hydrates may be used alone or in combination of two or more.
  Specific examples of metal halide hydrates include, for example, aluminum chloride (III) hexahydrate, chromium chloride (III) n hydrate, cerium chloride (III) n hydrate, thallium chloride (III) Examples thereof include tetrahydrate, titanium (III) chloride n hydrate, aluminum fluoride (III) n hydrate and the like. In addition, n is a hydration number and shows the coordination number of the water coordinated to the metal element.
Water-soluble compound (2): Water-soluble polyphenols
  The water-soluble polyphenols are not particularly limited. For example, flavonoids, catechins, tannins, isoflavones, anthocyanins, rutins, chlorogenic acids, gallic acids, lycopene, quercetin, myricetin, taxifosone, derivatives and multimers thereof, Examples thereof include a green tea extract, a red wine extract, a cacao extract, and a sunflower seed extract. Examples of tannin include hydrolyzable gallotannin, diphenylmethylolide tannin, condensed flovaphene tannin, and the like. Tannic acid is a hydrolyzable mixture of tannins. These water-soluble polyphenols may be used alone or in combination of two or more.
Water-soluble compound (3): Water-soluble vitamin B
  Water-soluble vitamin Bs are not particularly limited, but for example, vitamin B₁(Thiamine), vitamin B₂(Riboflavin), vitamin B₆(Pyridoxine), vitamin B₁₂(Cobalamin), derivatives of these vitamin Bs to nucleotides and nucleosides, or inorganic acid salts such as nitrates and hydrochlorides. These water-soluble vitamin Bs may be used alone or in combination of two or more.
Water-soluble compound (4): Water-soluble 1, 1 having a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group and a phosphonic acid (salt) group and a hetero atom are bonded to the same carbon atom -Substituted compounds
  The water-soluble 1,1-substituted compounds are not particularly limited. For example, aminopolycarboxylic acids (salts) having a structure in which the hydrophilic functional group is a carboxylic acid (salt) group and the hetero atom is a nitrogen atom. And aminopolyphosphonic acids (salts) having a structure in which the hydrophilic functional group is a phosphonic acid (salt) group and the hetero atom is a nitrogen atom.
  Aminopolycarboxylic acids (salts) are not particularly limited. For example, ethylenediaminetetraacetic acid (including salts thereof), hydroxyethylethylenediaminetriacetic acid (including salts thereof), and diethylenetriaminepentaacetic acid (including salts thereof). , Dihydroxyethylethylenediaminediacetic acid (including its salt), 1,3-propanediaminetetraacetic acid (including its salt), diethylenetriaminepentaacetic acid (including its salt), triethylenetetraaminehexaacetic acid (including its salt) Nitrilotriacetic acid (including its salt), gluconic acid (including its salt), hydroxyethyliminodiacetic acid (including its salt), L-aspartic acid-N, N-didiacetic acid (including its salt) , Dicarboxymethyl glutamic acid (including its salt), 1,3-diamino-2-hydroxypropanetetraacetic acid (its salt) Including), aminopolycarboxylic acids such as dihydroxyethyl glycine (including its salt); their metal salts; may be mentioned ammonium salts thereof, or the like. These aminopolycarboxylic acids (salts) may be used alone or in combination of two or more.
  The chemical structure of ethylenediaminetetraacetic acid (including its salt) exemplified above is shown in the following chemical formula (1).

(However, M¹~ M⁴Are selected from a hydrogen atom, an alkali metal, an alkaline earth metal, a transition metal, an ammonium group, and a primary to quaternary amine group, and may be the same or different. )
  The chemical structure of diethylenetriaminepentaacetic acid (including its salt) exemplified above is shown in the following chemical formula (2).

(However, M¹~ M⁵Are selected from a hydrogen atom, an alkali metal, an alkaline earth metal, a transition metal, an ammonium group, and a primary to quaternary amine group, and may be the same or different. )
  Aminopolyphosphonic acids (salts) are not particularly limited. For example, aminotrimethylenephosphonic acid (including salts thereof), hydroxyethanephosphonic acid (including salts thereof), hydroxyethylidene diphosphonic acid (salts thereof) ), Dihydroxyethylglycine (including its salt), phosphonobutane triacetic acid (including its salt), methylenephosphonic acid (including its salt) nitrilotrismethylenephosphonic acid (including its salt), ethylenediaminetetra (methylenephosphone) Acid) (including salts thereof) and the like; metal salts thereof; ammonium salts thereof and the like. These aminopolyphosphonic acids (salts) may be used alone or in combination of two or more.
  The aminopolycarboxylic acid salts and aminopolyphosphonates mean aminopolycarboxylic acid, metal salts of aminopolyphosphonic acid, amine salts, ammonium salts, and the like.
  The metal salts are compounds in which at least one proton of a carboxylic acid group or a phosphonic acid group that is an acidic group is replaced with a metal atom. Examples of the metal atom include alkali metals such as lithium, sodium and potassium (Group 1 metals in the periodic table); alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium (Group 2 metals in the periodic table); iron , Transition metals such as copper, manganese, zinc and cobalt. The obtained metal salts are easily available and may be used as food additives, and among these metal atoms, sodium, potassium and the like are preferable.
  Examples of the amine salts include compounds obtained by reacting at least one proton of a carboxylic acid group or phosphonic acid group, which is an acidic group, with an amine. The amine salt can also be expressed as a compound in which at least one proton of a carboxylic acid group or a phosphonic acid group which is an acidic group is replaced with a primary to quaternary amine group. Here, the primary amine group is a group having a +1 charge as a whole obtained by reacting a proton with a primary amine, and the secondary amine group is a whole obtained by reacting a proton with a secondary amine. As a group having a charge of +1, a tertiary amine group is a group having a charge of +1 as a whole obtained by reacting a proton with a tertiary amine, and a quaternary amine group is a tertiary amine group The proton is substituted with a hydrocarbon group, and is a group having a +1 charge as a whole.
  Examples of the primary to tertiary amine used as a raw material for the primary to tertiary amine group include (mono, di, or tri) alkylamines having 1 to 5 carbon atoms (for example, ethylamine, propylamine), and 2 to 10 carbon atoms. (Mono, di or tri) alkanolamine (eg, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, cyclohexyldiethanolamine, etc.), morpholine, cyclohexane having 5 to 20 carbon atoms There are alkylamines (for example, dicyclohexylamine), 3,3-dimethylpropanediamine, and the like.
  Examples of the quaternary amine group include dodecyltrimethylammonium, cocoalkyltrimethylammonium, hexadecyltomethylammonium, tallow alkyltrimethylammonium, octadecyltrimethylammonium, behenyltrimethylammonium, cocoalkyldimethylbenzylammonium, tetradecyldimethylbenzenammonium, coconut. Examples thereof include alkyldimethylbenzylammonium, octadecyldimethylbenzylammonium, cocoalkylalkylammonium, tetradecylammonium, octadecylammonium, triethylmethylammonium, dioleyldimethylammonium, didecyldimethylammonium, triethylmethylammonium and the like.
  The ammonium salts are compounds obtained by reacting ammonia with at least one proton of a carboxylic acid group or a phosphonic acid group which is an acidic group. In ammonium salts, protons are ammonium groups (—NH₄ ⁺It can also be expressed as a compound replaced with.
  Further, other water-soluble 1,1-substituted compounds are not particularly limited. For example, a 2-functional compound having a structure in which the hydrophilic functional group is a carboxylic acid (salt) group and the hetero atom is a nitrogen atom. Carboxypyridine, orotic acid, quinolinic acid, lutidine acid, isocincomeronic acid, dipicolinic acid, berberic acid, fusaric acid, orotic acid, etc .; the hydrophilic functional group is a hydroxyl (salt) group and the hetero atom is a nitrogen atom 2-hydroxypyridine, 6-hydroxynicotinic acid, citrazic acid and the like having a structure; compounds such as thiodiglycolic acid having a structure in which the hydrophilic functional group is a carboxylic acid (salt) group and the hetero atom is a sulfur atom Can be mentioned.
  In the water-soluble 1,1-substituted compounds, the hydrophilic functional group is preferably a carboxylic acid (salt) group and / or a phosphonic acid (salt) group, and the heteroatom is preferably a nitrogen atom and / or a sulfur atom.
  Water-soluble compounds are water-soluble compounds (1) such as titanium chloride (III), iron chloride (III), aluminum chloride (III) hexahydrate, antimony chloride (III), bismuth chloride (III); Water-soluble compounds such as acids (2); Vitamin B₂, Vitamin B₆Water-soluble compounds such as (3); ethylenediaminetetraacetic acid (including its salt), hydroxyethylethylenediaminetriacetic acid (including its salt), diethylenetriaminepentaacetic acid (including its salt), dihydroxyethylethylenediaminediacetic acid (including its salt) 1,3-propanediaminetetraacetic acid (including its salt), diethylenetriaminepentaacetic acid (including its salt), triethylenetetraamine hexaacetic acid (including its salt), nitrilotriacetic acid (including its salt) , Gluconic acid (including its salt), hydroxyethyliminodiacetic acid (including its salt), L-aspartic acid-N, N-didiacetic acid (including its salt), dicarboxymethylglutamic acid (including its salt) ), 1,3-diamino-2-hydroxypropanetetraacetic acid (including its salt), dihydroxyethylglycine (its ), Aminotrimethylene phosphonic acid (including its salt), hydroxyethane phosphonic acid (including its salt), dihydroxyethylglycine (including its salt), phosphonobutane triacetic acid (including its salt), methylene phosphonic acid Nitrilotrismethylenephosphonic acid (including its salt), 2-carboxypyridine, orotic acid, quinolinic acid, lutidine acid, isocincomeronic acid, dipicolinic acid, berberic acid, fusaric acid, orotic acid, 2 It is preferable that it is at least one selected from water-soluble compounds (4) such as -hydroxypyridine, 6-hydroxynicotinic acid, citrazic acid and thiodiglycolic acid because it is easily available and stable.
  Water-soluble compounds are aluminum chloride (III) hexahydrate, antimony chloride (III), bismuth chloride (III), vitamin B₆, 2-carboxypyridine, 2-hydroxypyridine, 6-hydroxynicotinic acid, orotic acid, thiodiglycolic acid, ethylenediaminetetraacetic acid (including its salt) and diethylenetriaminepentaacetic acid (including its salt) Is more preferable.
  In addition, the water-soluble compounds are aluminum chloride (III) hexahydrate, 2-carboxypyridine, 2-hydroxypyridine, 6-hydroxynicotinic acid, orotic acid, ethylenediaminetetraacetic acid (including its salt) and diethylenetriaminepentaacetic acid ( Particularly preferred is at least one selected from the group including salts thereof.
  Among the water-soluble compounds (1) to (4), the water-soluble compound (1) and / or the water-soluble compound (4) are preferable. When the polymerization is performed using at least two water-soluble compounds in combination, the polymerization is performed using only one water-soluble compound in any of the following three combinations (a) to (c). It is superior to the case in terms of the expansion ratio at the time of maximum expansion, repeated compression durability, and the effect of preventing aggregation of the heat-expandable microspheres generated during polymerization and the generation of scale in the polymerization reactor.
(A) A combination comprising at least two water-soluble compounds (1)
(B) A combination comprising at least two water-soluble compounds (4)
(C) A combination comprising at least one water-soluble compound (1) and one water-soluble compound (4)
  The amount of the water-soluble compound contained in the aqueous dispersion medium is not particularly limited, but is preferably 0.0001 to 1.0 part by weight, more preferably 0.0003 to 100 parts by weight of the polymerizable component. 0.8 part by weight, particularly preferably 0.001 to 0.5 part by weight. If the amount of the water-soluble compound is too small, the effect of the water-soluble compound may not be sufficiently obtained. Moreover, when there is too much quantity of a water-soluble compound, a polymerization rate may fall or the residual amount of the polymeric component which is a raw material may increase.
  As described above, the water-soluble compound is a component used as a polymerization aid, and agglomeration of thermally expandable microspheres generated during polymerization and generation of scale in the polymerization reactor (specifically, the polymerizable component In the polymerization, it acts to prevent clogging during filtration due to aggregates and polymer, and adhesion of the polymer to the inner wall of the polymerization reactor) due to the polymer firmly adhering to the outer shell surface of the thermally expandable microsphere. Inherently have. In the production method of the present invention, since such a water-soluble compound is used, it is also excellent in preventing aggregation of thermally expandable microspheres generated during polymerization and generation of scale in the polymerization reactor.
  In the present invention, the water-soluble compound may be used in combination with other polymerization aids. Other polymerization aids include dichromates (dichromic acid) such as ammonium dichromate (ammonium dichromate), sodium dichromate (sodium dichromate), potassium dichromate (potassium dichromate), etc. Salt); alkali metal nitrites such as sodium nitrite and potassium nitrite; radical inhibitors such as water-soluble ascorbic acid and derivatives thereof. For alkali metal nitrites, the standard values for the amount of harmful substances contained in groundwater are determined in the Enforcement Regulations of the Water Pollution Control Act for implementing the Water Pollution Control Act. Nitrite nitrogen and nitrate nitrogen A reference value of 10 ppm is defined for the total amount of Therefore, for nitrites used in conventional methods for producing thermally expandable microspheres, if the reaction waste liquid exceeds this concentration, it can be diluted with a large amount of water at the time of discharge, activated carbon, ion exchange resin, etc. It is necessary to perform adsorption treatment using
  In the production method of the present invention, since the polymerizable component is polymerized in the aqueous dispersion medium containing the water-soluble compound, the foaming agent charged at the time of production is effectively included in the thermally expandable microspheres without waste. can get. In the production method of the present invention, the encapsulation efficiency (%) showing a specific calculation method in the examples is preferably 88% or more, more preferably 90% or more, and particularly preferably 95% or more. .
  In addition to the water-soluble compound, the aqueous dispersion medium may contain the electrolyte described above, a dispersion stabilizer, and a dispersion stabilization auxiliary agent.
  The dispersion stabilizer is not particularly limited. For example, colloidal silica, colloidal calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, ferric hydroxide, calcium sulfate, barium sulfate, calcium oxalate, metasilicic acid. Calcium, calcium carbonate, barium carbonate, magnesium carbonate, calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, etc. phosphates, calcium pyrophosphate, aluminum pyrophosphate, pyrophosphates such as zinc pyrophosphate, difficulties such as alumina sol The dispersion stabilizer of a water-soluble inorganic compound can be mentioned. These dispersion stabilizers may be used alone or in combination of two or more, and the type thereof is appropriately selected in consideration of the particle diameter of the resulting heat-expandable microspheres, dispersion stability during polymerization, and the like. Of these, tricalcium phosphate, magnesium pyrophosphate obtained by the metathesis method, calcium pyrophosphate, and colloidal silica are preferable.
  The amount of the dispersion stabilizer is appropriately determined depending on the target particle size and is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the polymerizable component. Parts by weight.
  The dispersion stabilizing aid is not particularly limited, and examples thereof include a polymer type dispersion stabilizing aid, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant. Mention may be made of activators. These dispersion stabilizing aids may be used alone or in combination of two or more, and are appropriately selected in consideration of the particle diameter of the resulting heat-expandable microspheres, dispersion stability during polymerization, and the like.
  Examples of the polymer type dispersion stabilizing aid include, for example, a condensation product of diethanolamine and an aliphatic dicarboxylic acid, gelatin, polyvinyl pyrrolidone, methyl cellulose, polyethylene oxide, polyvinyl alcohol and the like.
  Examples of the cationic surfactant include alkylamines such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride.
  Examples of the anionic surfactant include fatty acid oils such as sodium oleate and castor oil potassium; alkyl sulfate salts such as sodium lauryl sulfate and ammonium lauryl sulfate; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; alkylnaphthalene sulfone. Examples include acid salts; alkane sulfonates; dialkyl sulfosuccinates alkyl phosphate esters; naphthalene sulfonate formalin condensates; polyoxyethylene alkyl phenyl ether sulfates; polyoxyethylene alkyl sulfates.
  Examples of the zwitterionic surfactant include alkyldimethylaminoacetic acid betaine, alkyldihydroxyethylaminoacetic acid betaine, and lauryldimethylamine oxide.
  Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxy Examples thereof include an ethylene-oxypropylene block polymer.
  The blending amount of the dispersion stabilizing aid is not particularly limited, but is preferably 0.0001 to 5 parts by weight, more preferably 0.0003 to 2 parts by weight with respect to 100 parts by weight of the polymerizable component.
  The aqueous dispersion medium is prepared, for example, by blending water such as ion exchange water with a water-soluble compound and, if necessary, a dispersion stabilizer and / or a dispersion stabilizing aid. The pH of the aqueous dispersion medium at the time of polymerization is appropriately determined depending on the type of the water-soluble compound, the dispersion stabilizer, and the dispersion stabilization aid. The aqueous dispersion medium during polymerization may be acidic, neutral, or alkaline, but is preferably acidic or neutral, and more preferably acidic. The pH of the aqueous dispersion medium during polymerization is usually 2 to 13, preferably 2 to 10, more preferably 2 to 8, still more preferably 2 to 6.5, particularly preferably 2 to 6, and most preferably 2 to 4. It is.
  In the present invention, the oily mixture is emulsified and dispersed in an aqueous dispersion medium so that spherical oil droplets having a predetermined particle diameter are prepared.
  Examples of the method for emulsifying and dispersing the oily mixture include, for example, a method of stirring with a homomixer (for example, manufactured by Special Machine Engineering Co., Ltd.), a homodisper (for example, manufactured by Special Machine Engineering Co., Ltd.), and the like, And general dispersion methods such as a method using a static dispersion device such as Noritake Engineering Co., Ltd., a membrane emulsification method, an ultrasonic dispersion method, a microchannel method, and the like.
  As a method of emulsifying and dispersing the oily mixture, for example, there is a method of using a continuous high-speed rotation high shear type stirring and dispersing machine disclosed in Japanese Unexamined Patent Publication No. 2000-191817. Hydrophobic substance and aqueous solution from the rotor side of a homogenizer equipped with a conical or frustoconical screen with liquid holes and a conical or frustoconical rotor with blade blades installed with clearance inside. A method of emulsifying and dispersing an oily mixture in an aqueous dispersion medium by rotating a rotor at high speed while supplying a medium and passing the clearance between the rotor and the screen and a liquid passage hole of the screen, that is, CLEARMIX ( Japanese Patent Application Laid-Open No. 2004-959, paragraphs 0005 to 0013 and FIGS. Arbitrariness.
  Next, suspension polymerization is started by heating the dispersion in which the oily mixture is dispersed as spherical oil droplets in the aqueous dispersion medium. During the polymerization reaction, it is preferable to stir the dispersion, and the stirring may be performed so gently as to prevent, for example, floating of the monomer and sedimentation of the thermally expandable microspheres after polymerization.
  Although superposition | polymerization temperature is freely set by the kind of polymerization initiator, Preferably it is 30-100 degreeC, More preferably, it is 40-90 degreeC, Most preferably, it controls in the range of 50-85 degreeC. The time for maintaining the reaction temperature is preferably about 0.1 to 20 hours. The initial polymerization pressure is not particularly limited, but is 0 to 5.0 MPa in gauge pressure, more preferably 0.1 to 3.0 MPa, and particularly preferably 0.2 to 2.0 MPa.
  After the completion of the polymerization reaction, if desired, the dispersion stabilizer is decomposed with hydrochloric acid or the like, and the resulting product (thermally expandable microspheres) is isolated from the dispersion by operations such as suction filtration, centrifugation, and centrifugal filtration. . Furthermore, the obtained thermally expandable microsphere-containing water-containing cake can be washed with water and dried to obtain thermally expandable microspheres.
  The method for producing thermally expandable microspheres of the present invention may further include a step of attaching a particulate filler to the outer surface of the outer shell. In the thermally expandable microsphere, when the fine particle filler adheres to the outer surface of the outer shell, dispersibility and fluidity can be improved during use.
  The fine particle filler may be either an organic or inorganic filler, and the type and amount thereof are appropriately selected according to the purpose of use.
  Examples of organic fillers include metal soaps such as magnesium stearate, calcium stearate, zinc stearate, barium stearate, lithium stearate; polyethylene wax, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid Synthetic waxes such as amide and hardened castor oil; resin powders such as polyacrylamide, polyimide, nylon, polymethyl methacrylate, polyethylene, and polytetrafluoroethylene.
  Inorganic fillers having a layered structure such as talc, mica, bentonite, sericite, carbon black, molybdenum disulfide, tungsten disulfide, graphite fluoride, calcium fluoride, boron nitride, etc .; , Alumina, mica, calcium carbonate, calcium hydroxide, calcium phosphate, magnesium hydroxide, magnesium phosphate, barium sulfate, titanium dioxide, zinc oxide, ceramic beads, glass beads, crystal beads and the like.
  These fine particle fillers may be used alone or in combination of two or more.
  The average particle diameter of the fine particle filler is preferably 1/10 or less of the average particle diameter of the heat-expandable microspheres before adhesion. Here, the average particle size means the average particle size of primary particles.
  The amount of the fine particle filler adhering to the thermally expandable microsphere is not particularly limited, but the function of the fine particle filler can be sufficiently exerted, and considering the size of the true specific gravity of the thermally expandable microsphere, etc. Is preferably 0.1 to 95 parts by weight, more preferably 0.5 to 60 parts by weight, particularly preferably 5 to 50 parts by weight, and most preferably 8 to 30 parts by weight per 100 parts by weight of the thermally expandable microspheres. Part.
  The fine particle filler can be attached by mixing the thermally expandable microspheres and the fine particle filler before adhesion. The mixing is not particularly limited, and can be performed using an apparatus having a very simple mechanism such as a container and a stirring blade. Moreover, you may use the powder mixer which can perform a general rocking | swiveling or stirring. Examples of the powder mixer include a powder mixer that can perform rocking stirring or stirring, such as a ribbon mixer and a vertical screw mixer. In recent years, super mixers (made by Kawata Co., Ltd.), high-speed mixers (made by Fukae Co., Ltd.) and Negura Machine (made by Seishin Enterprise Co., Ltd.), which are efficient and multifunctional powder mixers combined with a stirring device, are also available. ), SV mixer (manufactured by Shinko Environmental Solution Co., Ltd.) or the like may be used.
  In the production method of the present invention, when a water-soluble metal salt (hydrate) is used as the water-soluble compound, from the viewpoint of the invention, an outer shell made of a thermoplastic resin and an inner shell of the outer shell made of the thermoplastic resin are included. A method for producing thermally expandable microspheres comprising a foaming agent having a boiling point below the softening point, wherein scandium, cerium, titanium, zirconium, hafnium, vanadium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, Ion of at least one metal selected from iron, ruthenium, osmium, cobalt, rhodium, nickel, silver, gold, zinc, cadmium, boron, aluminum, gallium, indium, thallium, tin, lead, arsenic, antimony and bismuth 0 0.001 to 100 ppm and halogen ion 0.001 ppm or more In an aqueous dispersion medium, wherein the polymerizable component blowing agent and dispersing the oily mixture containing also a production method comprising the step of polymerizing the polymerizable component contained in the oily mixture.
  The “at least one metal” may be referred to as metal A below. Moreover, this manufacturing method may be called manufacturing method A below. The metal A ion is preferably a metal ion derived from a water-soluble metal salt (hydrate), and more preferably a metal ion derived from a metal halide and / or a hydrate thereof. In addition, about the manufacturing method A except the content demonstrated below, the description of the above-mentioned manufacturing method can be applied as it is.
  The amount of metal A ions contained in the aqueous dispersion medium is preferably 0.001 to 50 ppm, more preferably 0.001 to 10 ppm, and particularly preferably 0.01 to 10 ppm. If the amount of metal A ions is too small, the effects obtained in the present invention may not be obtained. On the other hand, if the amount of metal A ions is too large, the polymerization rate may decrease or the residual amount of the polymerizable component as a raw material may increase. The amount of halogen ions contained in the aqueous dispersion medium is preferably 0.01 ppm or more, more preferably 0.1 ppm or more, and particularly preferably 1 ppm or more. If the amount of halogen ions is small, the effects obtained by the present invention may not be obtained.
  By polymerizing the polymerizable component in an aqueous dispersion medium containing 0.001 to 100 ppm of metal A ions and 0.001 ppm of halogen ions, the expansion ratio is high, and excellent repeated compression durability when thermally expanded. Thermally expandable microspheres that become hollow fine particles can be efficiently produced. Further, in the production method A, it is possible to prevent aggregation of generated particles during polymerization and generation of scale in the polymerization reactor.
  When the aqueous dispersion medium does not contain an electrolyte containing halogen ions such as lithium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, the amount of halogen ions is preferably 0.001 to 50 ppm, more preferably Is 0.001 to 10 ppm, particularly preferably 0.01 to 10 ppm.
[Thermal expandable microsphere and its use]
  As shown in FIG. 1, the thermally expandable microsphere of the present invention includes an outer shell (shell) 11 made of a thermoplastic resin and a foaming agent (core) 12 encapsulated in the shell and vaporized below the softening point of the thermoplastic resin. The thermally expandable microsphere exhibits thermal expandability (property that the entire microsphere expands by heating) as a whole microsphere. The thermoplastic resin, the polymerizable component that is polymerized to become a thermoplastic resin, the foaming agent, and the like are as described above.
  The expansion ratio at the time of maximum expansion of the thermally expandable microspheres of the present invention is 50 times or more, preferably 55 times or more, more preferably 60 times or more, still more preferably 65 times or more, particularly preferably 70 times or more, Most preferably, it is 75 times or more. If the expansion ratio at the time of maximum expansion of the thermally expandable microsphere is less than 50 times, the thermally expandable microsphere has low thermal expandability, and the volume increase at the time of thermal expansion is not sufficient, and further, the inner capsule holding performance and solvent resistance The performance may be lowered, which is not preferable.
  The expansion ratio is generally the most basic physical property of thermally expandable microspheres, and is an indispensable physical property for the purpose of reducing the weight and increasing the volume of hollow microparticles obtained by thermally expanding thermally expandable microspheres. is there. There are various definitions of the expansion ratio, but the expansion ratio at the maximum expansion is calculated by dividing the true specific gravity of the hollow microparticles at the maximum expansion by the true specific gravity of the thermally expandable microspheres before expansion. Is defined as a percentage.
  The expansion ratio at the time of maximum expansion is high. Generally, the thickness of the outer shell of the thermally expandable microsphere decreases as it expands. This means that the encapsulated foaming agent can be retained without leaking. That is, a high expansion ratio at the time of maximum expansion in the physical properties of the thermally expandable microspheres is synonymous with a high foaming agent holding performance and a good outer shell being formed. It is also known that thermally expandable microspheres having a good outer shell have high solvent resistance without losing thermal expansion performance even when exposed to various solvents. Therefore, the evaluation of the expansion ratio at the time of maximum expansion is a very important evaluation item in the physical property evaluation of the thermally expandable microsphere.
  In the thermally expandable microsphere of the present invention, the repeated compression durability of the hollow fine particles obtained by thermally expanding the microsphere is 75% or more, preferably 78% or more, more preferably 80% or more, and still more preferably 83%. Above, especially preferably 85% or less, most preferably 88% or more. When the repeated compression durability of the hollow fine particles is less than 75%, the molded article such as a molded product or a coating film obtained from the thermally expandable microsphere as a raw material, light weight, porosity, sound absorption, heat insulation, heat Various physical properties such as conductivity, design properties, strength, etc. are reduced, and inclusion holding performance and solvent resistance performance are lowered.
  The repeated compression durability is obtained by thermally expanding thermally expandable microspheres, and measuring the hollow fine particles having a true specific gravity of (0.025 ± 0.001) g / cc according to the measurement method described in detail in Examples. Is done. In addition, as shown in the examples, an internal injection method, which is a type of dry heating expansion method described later, is employed as a method for obtaining hollow fine particles by thermally expanding thermally expandable microspheres in order to repeatedly measure compression durability. Is done. The reason why the internal injection method is adopted is that the obtained hollow microparticles are in a dry state, and therefore the step of drying the hollow microparticles as in the wet heating expansion method is unnecessary, and the dispersibility of the obtained hollow microparticles Is an excellent point.
  The true specific gravity of the thermally expandable microsphere before expansion is generally about 1 g / cc. In the thermally expandable microsphere of the present invention, the expansion ratio at the time of maximum expansion is 50 times or more, so that the true specific gravity of the hollow fine particles obtained at the time of maximum expansion is about 0.02 g / cc or less. Actually, when the true specific gravity of the hollow fine particles is about 0.02 g / cc, it may be difficult to determine whether the hollow particles are superior or inferior even if repeated compression durability is evaluated. On the other hand, in hollow fine particles having a true specific gravity of (0.025 ± 0.001) g / cc, which is highly unlikely to cause maximum expansion, the degree of expansion is somewhat suppressed, and repeated compression durability evaluation The difference between superiority and inferiority becomes clear. Under such circumstances, repeated compression durability is measured for hollow fine particles having a true specific gravity (0.025 ± 0.001) g / cc.
  Repeated compression durability is a physical property value that evaluates the durability of hollow fine particles against stress generated when a base material component and hollow fine particles, which will be described later, are mixed or when a composition comprising a base material component and hollow fine particles is formed. It is. It can be said that evaluating the repeated compression durability of the hollow fine particles is synonymous with evaluating the durability against the repeated bending of the outer shell of the hollow fine particles. The fact that the outer shell of the hollow fine particles has high durability against repeated bending means that the outer shell of the hollow fine particles is formed of a thermoplastic resin that is uniform in material without partially weakening during repeated bending. It means that. The fact that the outer shell of the hollow microparticles is uniform in material is synonymous with the fact that the outer shell of the hollow microparticles, which is the raw material of the hollow microparticles, has a uniform and good outer shell. . It has also been found that the thermally expandable microspheres having a uniform and good outer shell in material quality do not impair the thermal expansion performance even when exposed to various solvents and have high solvent resistance. Conversely, if the outer shell is uneven in material and has weak parts, the blowing agent blows out from the part, or when exposed to various solvents, the part is swollen and the thermal expansion performance is impaired. Sometimes.
  As described above, when the hollow fine particles having high repeated compression durability and / or the thermally expandable microspheres that are the raw materials thereof are mixed with the base component, the base component and the hollow fine particles and / or the thermally expandable microspheres When molding or coating a composition comprising the above, the durability against the generated stress is increased, and damage due to the stress is less likely to occur.
  The thermally expandable microsphere preferably has the following physical properties.
  The average particle diameter of the heat-expandable microsphere is not particularly limited because it can be designed freely according to the use, but is usually 1 to 100 μm, preferably 2 to 80 μm, more preferably 3 to 60 μm, particularly preferably. Is 5 to 50 μm or more.
  The coefficient of variation CV of the particle size distribution of the heat-expandable microspheres is not particularly limited, but is preferably 35% or less, more preferably 30% or less, and particularly preferably 25% or less. The variation coefficient CV is calculated by the following calculation formulas (1) and (2).
  CV = (s / <x>) × 100 (%) (1)

(In the formula, s is the standard deviation of the particle diameter, <x> is the average particle diameter, x_iIs the i-th particle diameter, and n is the number of particles. )
  The encapsulating rate of the foaming agent encapsulated in the thermally expandable microspheres is not particularly limited because it can be freely designed according to the application, but preferably 2 to 2 with respect to the weight of the thermally expandable microspheres. It is 60% by weight, more preferably 5 to 50% by weight, particularly preferably 8 to 45% by weight.
  Although the thermally expansible microsphere of this invention can be manufactured with the manufacturing method demonstrated above, it is not limited to this manufacturing method. It is considered that the thermally expandable microspheres of the present invention can be produced by, for example, an interfacial polymerization method, a reverse phase emulsification method, an emulsion polymerization method or the like. Further, as a method of not producing droplets in an aqueous dispersion medium, it can be considered that it can be produced by, for example, a submerged drying method, a coacervation method, a spray drying method, a dry mixing method, or the like. It is also considered possible to produce the polymer by graft polymerizing the outer shell of thermally expandable microspheres obtained by a production method different from the present invention.
  By thermally expanding the thermally expandable microspheres of the present invention and / or the thermally expandable microspheres obtained by the production method of the present invention, thermally expanded microspheres (hollow microparticles) can be manufactured. The method for producing the hollow fine particles is not particularly limited, and any of a dry heat expansion method and a wet heat expansion method may be used.
  Examples of the dry heating expansion method include an internal injection method described in Japanese Patent Application Laid-Open No. 2006-213930. This internal injection method includes a step (injection step) of causing a gas fluid containing thermally expandable microspheres to flow through a gas introduction pipe provided with a dispersion nozzle at the outlet and installed inside the hot air flow, and to be injected from the dispersion nozzle. , The step of causing the gaseous fluid to collide with a collision plate installed downstream of the dispersion nozzle and dispersing the thermally expandable microspheres in the hot air flow (dispersion step); It is a dry-type heating expansion method including a step (expansion step) of heating and expanding above the expansion start temperature in a hot air flow. The internal injection method is preferable because hollow fine particles having uniform physical properties can be obtained regardless of the type of thermoplastic resin constituting the outer shell of the thermally expandable microspheres as a raw material. Details of the internal injection method are described in the examples.
  As another dry heating expansion method, there is a method described in Japanese Patent Application Laid-Open No. 2006-96963. Examples of the wet heating expansion method include the method described in Japanese Patent Application Laid-Open No. 62-201231.
  The average particle size of the hollow fine particles is not particularly limited because it can be designed freely according to the use, but is preferably 1 to 1000 μm, more preferably 5 to 800 μm, and particularly preferably 10 to 500 μm. Further, the coefficient of variation CV of the particle size distribution of the hollow fine particles is not particularly limited, but is preferably 30% or less, more preferably 27% or less, and particularly preferably 25% or less.
  The composition of the present invention comprises a base component and thermally expandable microspheres and / or hollow fine particles.
  The base material component is not particularly limited. For example, rubbers such as natural rubber, butyl rubber, and silicon rubber; thermosetting resins such as epoxy resins and phenol resins; modified silicones, urethanes, polysulfides, acrylics, Examples thereof include silicone-based sealing materials; ethylene-vinyl acetate copolymer-based, vinyl chloride-based and acrylic coating components; and inorganic materials such as cement, mortar, and cordierite. The composition of the present invention can be prepared by mixing these base material components with thermally expandable microspheres and / or hollow fine particles.
  Examples of the use of the composition of the present invention include a molding composition, a coating composition, a clay composition, a fiber composition, an adhesive composition, and a powder composition.
  The molded product of the present invention is obtained by molding this composition. Examples of the molded article of the present invention include molded articles such as molded articles and coating films. In the molded product of the present invention, various physical properties such as lightness, porosity, sound absorption, heat insulation / thermal conductivity, electrical conductivity, design properties, impact absorption, and strength are improved.

上記表において、以下の略号が使用されている。
＊１：重合後の反応混合物に異常はなく良好
＊２：重合後の反応混合物の大半が凝集／固化
ＥＤＴＡ：エチレンジアミン４酢酸塩・４Ｎａ・４Ｈ_２Ｏ（キレスト株式会社製、商品名：キレスト３Ｄ）
ＧＬＤＡ：ジカルボキシメチルグルタミン酸・４Ｎａ（キレスト株式会社製、商品名：キレストＣＭＧ−４０）
ＰＢＴＣ：ホスホノブタン三酢酸・３Ｎａ（キレスト株式会社製、商品名：キレストＰＨ−４３０）
ＥＤＴＭＰ：テトラキス（ホスホノメチル）エチレンジアミン（キレスト株式会社製、商品名：キレストＰＨ−５４０）
タンニン：タンニン酸（和光純薬工業株式会社製）
ビタミンＢ_６塩酸塩：ピリドキシン塩酸塩（和光純薬工業株式会社製）
没食子酸：没食子酸水和物（和光純薬工業株式会社製）
重クロム酸カリウム：二クロム酸カリウム（和光純薬工業株式会社製）
ＤＴＰＡ：ジエチレントリアミン五酢酸・５Ｎａ（ナガセケムテックス株式会社製、商品名：クレワットＤＰ−８０）
チオジグリコール酸：和光純薬工業株式会社製
２−ヒドロキシピリジン：和光純薬工業株式会社製
２−カルボキシピリジン：和光純薬工業株式会社製、商品名：２−ピリジンカルボン酸
ビタミンＢ_２：リボフラビン（和光純薬工業株式会社製、商品名：ビタミンＢ_２）
アジピン酸−ジエタノールアミン縮合物：純度５０％水溶液
ＡＮ：アクリロニトリル
ＭＡＮ：メタクリロニトリル
ＭＭＡ：メチルメタクリレート
ＭＡ：メチルアクリレート
ＶＣｌ_２：塩化ビニリデン
ＩＢＸ：イソボルニルメタクリレート
ＭＡＡ：メタクリル酸
ＰＭＩ：Ｎ−フェニルマレイミド（株式会社日本触媒製）
ＥＤＭＡ：ジエチレングリコールジメタクリレート（三菱レイヨン（株）製）
ＴＭＰ：トリメチロールプロパントリメタクリレート（共栄社化学（株）製）
４ＥＧ−Ａ：ＰＥＧ＃２００ジメタクリレート（共栄社化学（株）製）
ＡＩＢＮ：２，２′−アゾイソブチルニトリル（日本ヒドラジン工業（株）製）Ｓ（ＢＰ）：ジ−ｓｅｃ−ブチルパーオキシジカーボネート（ルパゾール２２５またはＳ（ＢＰ）、純度５０％、アルケマ吉冨（株）製）
ＯＰＰ：ジ−２−エチルヘキシルパーオキシジカーボネート（パーロイルＯＰＰ、純度７０％、日本油脂（株）製）
ＩＰＰ：ジイソプロピルパーオキシジカーボネート（パーロイルＩＰＰ−５０、純度５０％、日本油脂（株）製）
〔実施例Ｄ１〕
実施例Ａ１３で得られた熱膨張性微小球３重量％と、ポリプロピレン（密度０．９ｇ／ｃｍ^３、メルトフローレート１４ｇ／１０分（２３０℃））９７重量％をスーパーミキサー（（株）カワタ社製）に投入し、６０℃以上に温度上昇しない攪拌速度（約３６０ｒｐｍ）で約１ｍｉｎ間混合を行った。得られた混合物を型締力約８０トン、スクリュー径３２ｍｍを有する射出成形機を用いて、射出圧力約１０００ｋｇ／ｃｍ^２で射出成形を行い、直径９８ｍｍ×３ｍｍの円盤状の成形物を得た。温度条件は１９０℃、２１０℃、２３０℃、２５０℃にて行い、得られた成形物の密度の測定および軽量化率の算出を行った。結果を表１１に示す。
〔比較例Ｄ１〕
実施例Ｄ１において実施例Ａ１３で得られた熱膨張性微小球の代わりに、比較例Ａ４で得られた熱膨張性微小球を用いた以外は実施例Ｄ１と同様に成形物を得た。結果を表１１に示す。
〔実施例Ｄ２〕
（熱膨張性微小球３０重量％含有マスターバッチの製造方法）
実施例Ａ１３で得られた熱膨張性微小球３０重量％とポリエチレン（ダウ・ケミカル日本（株）社製、ＥＮＧＡＧＥ ＳＭ８４００、密度０．９ｇ／ｃｍ^３、ＤＳＣ融点６３．３℃）７０重量％とパラフィンオイル（１５０Ｓ）２重量％をスーパーミキサー（（株）カワタ社製）に投入し、６０℃以上に温度上昇しない攪拌速度（約３６０ｒｐｍ）で約１ｍｉｎ間混合を行った。
得られた混合物を、２軸スクリュー押出機（池貝（株）社製；ＧＴ−１１０）に入れ、スクリュー回転数３０ｒｐｍ、ダイス部温度９０℃の条件で混練し直径３〜３．５ｍｍの太さで押出した。そして、ダイスから押出した混合物は、ダイス出口に取り付けた回転ハンマーで直ちにホットカットした。さらに、ホットカット直後のペレットは、６角形の回転体を備えたペレットクーラーに入れ、回転させながら５０℃以下の温度になるまで冷却した。このようにして、直径３〜３．５ｍｍ、長さ２ｍｍ〜４ｍｍである、実施例Ａ１３で得られた熱膨張性微小球を３０重量％含有するマスターバッチを作製した。
（発泡成形品の作製）
実施例Ｄ２における発泡成形品の作製は、実施例Ｄ１の熱膨張性微小球３重量％とポリプロピレン９７重量％の混合物を原料として使用する代わりに、上記マスターバッチ１０重量％とポリプロピレン９０重量％との混合物を原料として使用する以外は実施例Ｄ１と同様の方法で行った。得られた成形物の密度の測定と軽量化率の算出を行った。結果を表１１に示す。
〔比較例Ｄ２〕
比較例Ｄ２では、実施例Ｄ２において実施例Ａ１３で得られた熱膨張性微小球の代わりに、比較例Ａ４で得られた熱膨張性微小球を使用した以外は同様の方法で発泡成形品を作製した。得られた成形物の密度の測定と軽量化率の算出を行った。結果を表１１に示す。

表１１の結果より、本発明の熱膨張性微小球を樹脂の軽量化に使用する際、非常に優れた軽量化性能を有し、またマスターバッチ作製時の混合応力に対する耐久性が非常に高いことが明確である。
〔実施例Ｄ３〕
（中空微粒子の製造方法）
実施例Ａ２１で得られた熱膨張性微小球を５重量％含有する水分散液（スラリー）を調製した。この水分散液を日本国特開昭６２−２０１２３１号公報に記載された湿式加熱膨張法で膨張し、中空微粒子を得た。下記に詳細を示す。
スラリーをスラリー導入管から発泡管（直径１６ｍｍ容積１２０ｍｌ、ＳＵＳ３０４ＴＰ製）に５Ｌ／ｍｉｎの流量を示すように送り込み、さらに水蒸気（温度：１４７℃、圧力：０．３ＭＰａ）を蒸気導入管より供給し、スラリーと混合して、湿式加熱膨張した。混合後のスラリー温度を１２０℃に調節し、圧力は０．１８ＭＰａであった。
得られた中空微粒子を含むスラリーを発泡管突出部から流出させ、冷却水（水温１５℃）と混合して、５０〜６０℃に冷却した。冷却したスラリー液を遠心脱水機で脱水して、湿化した中空微粒子を含む組成物（水１５重量％含有）を得た。
セラミック原料としてコージェライト２８３ｇ、メチルセルロース１４．２ｇおよび上記で得られた組成物４２．５ｇを混練して、押出成形可能なセラミック組成物を調製した後、得られたセラミック組成物を押出成形法により賦形して、未焼成のセラミック成形体（坏土）を成形した。
次いで、得られたセラミック成形体（坏土）の坏土密度を以下の方法で測定し、中空微粒子とセラミック材料との混合時と、中空微粒子とセラミック材料からなる組成物の押出成形時とに発生する応力による破壊に対する耐久性を評価した。その結果は表１２に示すとおりであった。
（坏土密度の測定方法）
セラミック成形体（坏土）を一定体積になるように裁断し、その重量を測定した後、測定された重量を体積で除して、坏土密度を算出し、下記判定基準により中空微粒子について、混合および押出成形時に発生する応力による破壊に対する耐久性を評価した。坏土密度が低いほど中空微粒子の混合および押出成形時に発生する応力による破壊に対する耐久性が優れていることになる。
（判定基準）
◎‥‥坏土密度が１．４ｇ／ｃｍ^３未満。
○‥‥坏土密度が１．４ｇ／ｃｍ^３以上１．６ｇ／ｃｍ^３未満。
△‥‥坏土密度が１．６ｇ／ｃｍ^３以上１．７ｇ／ｃｍ^３未満。
×‥‥坏土密度が１．７ｇ／ｃｍ^３以上。
〔実施例Ｄ４および比較例Ｄ３〜Ｄ４〕
実施例Ｄ４および比較例Ｄ３〜Ｄ４では、実施例Ｄ３において、表１２に示すように原料である熱膨張性微小球をそれぞれ変更する以外は、実施例Ｄ３と同様にして評価を行った。

表１２の結果より、本発明の熱膨張性微小球から得られた中空微粒子はセラミック材料などの無機材料と混合し使用する際、非常に優れた性能を有することが明らかである。
〔実施例Ｄ５〕
実施例Ｂ１と同様の配合比率、反応条件でスケールアップ反応し、２０ｋｇの乾燥した熱膨張性微小球を得た。熱膨張性微小球の物性は、実施例Ｂ１で得られた熱膨張性微小球と同等であった。
上記で得られた熱膨張性微小球２ｋｇと重質炭酸カルシウム（白石カルシウム株式会社製、ホワイトンＳＢアカ、平均粒子径：１．８μｍ）８ｋｇをＳＶミキサー（神鋼環境ソリューション株式会社製、内容量：３０Ｌ）に投入し、１０分間混合した。その後、得られた混合物をレーディゲミキサー（株式会社マツボー製）に投入し、ジャケット温度１９０℃で１０分間加熱し、混合物の温度が１５０℃に到達した時点で冷却し、組成物を得た（平均粒子径：１０８μｍ、真比重：０．１５ｇ／ｃｃ）。
得られた組成物を用いて、中空微粒子の繰り返し圧縮耐久性の評価を行った。
測定方法は、上記〔繰り返し圧縮耐久性の測定〕で中空微粒子２．００ｍｇの代わりに上記組成物を１０．０ｍｇ用いる以外は同様の方法で測定した。結果を表１３に示す。
〔比較例Ｄ５〕
比較例Ｄ５は、実施例Ｄ５において実施例Ｂ１の配合比率で熱膨張性微小球を作製する代わりに比較例Ｂ４の配合比率で熱膨張性微小球を作製した以外は同様の方法で行った。結果を表１３に示す。

表１３の結果より、本発明の熱膨張性微小球を原料とした組成物の繰り返し圧縮耐久性においても非常に良好な性能を示すことが明らかである。
〔実施例Ｄ６〕
（未膨張塗膜の作製）
実施例Ａ１７で得られた熱膨張性微小球を濃度５５重量％のエチレン・酢酸ビニル共重合体（ＥＶＡ；エチレン／酢酸ビニル＝３０／７０重量％）に対して１０重量％加えて（ＥＶＡ９重量部に対して熱膨張性微小球１重量部）塗布液を調製した。この塗布液を両面アート紙に２００μｍのギャップを有するコーターで塗布する。塗布した両面アート紙を乾燥して、実施例Ａ１７で得られた熱膨張性微小球を１０重量％含有する２００μｍ厚みの未膨張塗膜を両面アート紙上に作製した。
（膨張塗膜の作製）
上記未膨張塗膜が形成された両面アート紙を、所定温度のギヤ式オーブン中で所定時間加熱して、膨張塗膜が形成された両面アート紙を得た。
（発泡倍率の測定方法）
未膨張塗膜が形成された両面アート紙の厚み（Ａ）と膨張塗膜が形成された両面アート紙の厚み（Ｂ）とをそれぞれ計測して、発泡前後の厚み倍率（＝Ｂ／Ａ）を計算し、意匠性を評価した。その結果を表１４に示す。厚み倍率が高いほど意匠性に優れていることになる。
〔実施例Ｄ７〜Ｄ８および比較例Ｄ６〜Ｄ７〕
実施例Ｄ７〜Ｄ８および比較例Ｄ６〜Ｄ７では、実施例Ｄ６において、表１３に示すように原料である熱膨張性微小球をそれぞれ変更する以外は、実施例Ｄ６と同様にして評価を行った。

表１４の結果より、本発明の熱膨張性微小球から得られた膨張塗膜は厚みに非常に富み意匠性に非常に優れた性能を有することが明らかである。
〔実施例Ｄ９〕
（未膨張ＰＶＣ塗膜の作製）
実施例Ａ１７で得られた熱膨張性微小球１重量部に対してポリ塩化ビニル（ＰＶＣ）（新第一塩化ビニル社製）２５重量部とＤＩＮＰ（新日本理化社製）５０重量部と炭酸カルシウム（備北粉化工業社製）２５重量部を加えてコンパウンドを調製した。調製したコンパウンドを１．５ｍｍ厚みで０．８ｍｍ厚みの電着塗装鉄板上に敷いたテフロンシート（ＥＧＦ−５００−１０）上に塗工してギヤ式オーブンにて１００℃で１０分間加熱してゲル化させ、テフロンシートから剥がした。このようにして、未膨張ＰＶＣ塗膜を作製した。
（膨張ＰＶＣ塗膜の作製）
上記未膨張ＰＶＣ塗膜を、所定温度のギヤ式オーブン中で所定時間加熱して、膨張ＰＶＣ塗膜を得た。
（発泡倍率の測定方法）
未膨張ＰＶＣ塗膜の比重（Ａ）と膨張ＰＶＣ塗膜の比重（Ｂ）をそれぞれ計測して、発泡前後の比重低下率（＝（Ａ−Ｂ）＊１００／Ａ）を計算し、軽量性を評価した。その結果を表１５に示す。比重低下率が大きいほど、軽量化、クッション性、弾力性、衝撃強度等の物性に優れていることになる。
〔実施例Ｄ１０〜Ｄ１１および比較例Ｄ８〜Ｄ９〕
実施例Ｄ１０〜Ｄ１１および比較例Ｄ８〜Ｄ９では、実施例Ｄ９において、表１５に示すように原料である熱膨張性微小球をそれぞれ変更する以外は、実施例Ｄ９と同様にして評価を行った。

表１５の結果より、本発明の熱膨張性微小球から得られた膨張ＰＶＣ塗膜は軽量化、クッション性、弾力性、衝撃強度等の物性に非常に優れた性能を有することが明らかである。
〔実施例Ｄ１２〕
（未膨張アクリル塗膜の作製）
実施例Ａ１７で得られた熱膨張性微小球１重量部に対して、メタクリル樹脂パウダー（日本ゼオン社製）５０重量部およびアセチルトリブチルシトレート４０重量部と炭酸カルシウム（備北粉化工業社製）１０重量部を加えてコンパウンドを調製した。調製したコンパウンドを１．５ｍｍ厚みで０．８ｍｍ厚みの電着塗装鉄板上に敷いたテフロンシート（ＥＧＦ−５００−１０）上に塗工してギヤ式オーブンにて１００℃で１０分間加熱してゲル化させ、テフロンシートから剥がした。このようにして、未膨張アクリル塗膜を作製した。
（膨張アクリル塗膜の作製）
上記未膨張アクリル塗膜を、所定温度のギヤ式オーブン中で所定時間加熱して、膨張アクリル塗膜を得た。
（発泡倍率の測定方法）
未膨張アクリル塗膜の比重（Ａ）と膨張アクリル塗膜の比重（Ｂ）をそれぞれ計測して、発泡前後の比重低下率（＝（Ａ−Ｂ）＊１００／Ａ）を計算し、軽量性を評価した。その結果を表１６に示す。比重低下率が大きいほど、軽量化、クッション性、弾力性、衝撃強度等の物性に優れていることになる。
〔実施例Ｄ１３〜Ｄ１４および比較例Ｄ１０〜Ｄ１１〕
実施例Ｄ１３〜Ｄ１４および比較例Ｄ１０〜Ｄ１１では、実施例Ｄ１２において、表１６に示すように原料である熱膨張性微小球をそれぞれ変更する以外は、実施例Ｄ１２と同様にして評価を行った。

表１６の結果より、本発明の熱膨張性微小球から得られた膨張アクリル塗膜は軽量化、クッション性、弾力性、衝撃強度等の物性に非常に優れた性能を有することが明らかである。Examples of the present invention will be specifically described below. The present invention is not limited to these examples.
With respect to the thermally expandable microspheres and hollow fine particles produced in the following examples and comparative examples, the physical properties were measured in the following manner, and the performance was further evaluated.
[Measurement of average particle size and particle size distribution]
A laser diffraction particle size distribution analyzer (HEROS & RODOS manufactured by SYMPATEC) was used. The dispersion pressure of the dry dispersion unit was 5.0 bar, the degree of vacuum was 5.0 mbar, and measured by a dry measurement method, and the median diameter (D50 value) was defined as the average particle diameter.
[Measurement of moisture content of thermally expandable microspheres]
As a measuring apparatus, a Karl Fischer moisture meter (MKA-510N type, manufactured by Kyoto Electronics Industry Co., Ltd.) was used for measurement.
[Measurement of encapsulation rate of foaming agent enclosed in thermally expandable microspheres]
1.0 g of thermally expandable microspheres were placed in a stainless steel evaporation dish having a diameter of 80 mm and a depth of 15 mm, and the weight (W ₁ ) was measured. 30 ml of acetonitrile was added and dispersed uniformly, left at room temperature for 30 minutes, then heated at 120 ° C. for 2 hours, and the weight (W ₂ ) after drying was measured. The encapsulation rate of the foaming agent is calculated by the following formula.
Inclusion rate (% by weight) = (W ₁ −W ₂ ) (g) /1.0 (g) × 100− (water content) (% by weight)
(In the formula, the moisture content is measured by the above method.)
[Calculation of inclusion efficiency]
The encapsulating efficiency of the foaming agent is the ratio of the encapsulating rate (G ₂ ) of thermally expandable microspheres obtained by polymerizing this oily mixture to the weight ratio (G ₁ ) of the foaming agent to the weight of the oily mixture before polymerization. It is a ratio and is calculated by the following formula.
Inclusion efficiency (%) = G ₂ / G ₁ × 100
[Measurement of true specific gravity]
The true specific gravity of the thermally expandable microsphere and the hollow fine particles obtained by thermally expanding the microsphere was measured by the following measuring method.
The true specific gravity was measured by an immersion method (Archimedes method) using isopropyl alcohol in an atmosphere having an environmental temperature of 25 ° C. and a relative humidity of 50%.
Specifically, the volumetric flask having a capacity of 100 cc was emptied and dried, and the weight of the volumetric flask (WB ₁ ) was weighed. After accurately filling the weighed measuring flask with isopropyl alcohol to the meniscus, the weight (WB ₂ ) of the measuring flask filled with 100 cc of isopropyl alcohol was weighed.
Further, the volumetric flask with a capacity of 100 cc was emptied and dried, and the weight of the volumetric flask (WS ₁ ) was weighed. The weighed volumetric flask was filled with about 50 cc of particles, and the weight (WS ₂ ) of the volumetric flask filled with the particles was weighed. Then, the weight (WS ₃ ) after accurately filling the meniscus with isopropyl alcohol to prevent bubbles from entering the volumetric flask filled with particles was weighed. Then, the obtained WB ₁ , WB ₂ , WS ₁ , WS ₂ and WS ₃ were introduced into the following equation, and the true specific gravity (d) of the particles was calculated.
d = {(WS ₂ −WS ₁ ) × (WB ₂ −WB ₁ ) / 100} / {(WB ₂ −WB ₁ ) − (WS ₃ −WS ₂ )}
Above, the true specific gravity of each was calculated using thermally expandable microspheres or hollow fine particles as particles.
[Measurement of expansion start temperature and maximum expansion temperature]
As a measuring device, DMA (dynamic viscoelasticity measuring device: DMA Q800 type, manufactured by TA instruments) was used. Place 0.5 mg of thermally expandable microspheres in an aluminum cup with a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, and place an aluminum lid with a diameter of 5.6 mm and a thickness of 0.1 mm on top of the microsphere layer. A sample was prepared. The sample height was measured in a state where a force of 0.01 N was applied to the sample with a pressurizer from above. In a state where a force of 0.01 N was applied by a pressurizer, heating was performed from 20 to 300 ° C. at a rate of temperature increase of 10 ° C./min, and the amount of displacement of the pressurizer in the vertical direction was measured. The displacement start temperature in the positive direction was defined as the expansion start temperature, and the temperature when the maximum displacement was indicated was defined as the maximum expansion temperature.
[Measurement of true specific gravity at maximum expansion]
A flat box with a bottom of 12 cm in length, 13 cm in width and 9 cm in height is made of aluminum foil, and 1.0 g of thermally expandable microspheres are uniformly placed therein, and obtained by measuring the expansion start temperature. The temperature was raised by 5 ° C. from the starting temperature of expansion, heated at each temperature for 1 minute, and then the true specific gravity of the expanded thermally expandable microspheres (hollow microparticles) was measured according to the above measurement method. Among them, the one showing the lowest true specific gravity was taken as the true specific gravity at the time of maximum expansion.
[Evaluation of expansion ratio at maximum expansion]
The expansion ratio (times) at the time of maximum expansion is lower than the true specific gravity (d _c ) of the thermally expandable microspheres before expansion and the true specific gravity (d _max ) of the thermally expandable microspheres (hollow particles) after expansion. Calculated by introducing into the formula. In addition, each true specific gravity was measured according to the said measuring method.
Maximum expansion when the expansion ratio _(times) = _{d c /} d _max
[Repeated compression durability]
As described above, an internal injection method described in Japanese Patent Application Laid-Open No. 2006-213930 was adopted as a method for producing hollow fine particles used for repeated compression durability measurement. Specifically, using the manufacturing apparatus provided with the foaming process part shown in FIG. The hollow fine particles obtained were then repeatedly measured for compression durability by the following method.
(Explanation of foaming process part)
This foaming process section includes a gas introduction pipe (not shown) provided with a dispersion nozzle 4 at the outlet and disposed in the center, an impingement plate 5 installed downstream of the dispersion nozzle 4, and a gas introduction pipe. An overheating prevention cylinder 3 arranged at intervals around the periphery and a hot air nozzle 1 arranged at intervals around the overheating prevention cylinder 3 are provided. In this foaming process section, a gas fluid 6 containing thermally expandable microspheres is made to flow in the direction of the arrow in the gas introduction tube, and the space formed between the gas introduction tube and the overheating prevention cylinder 3 is thermally expanded. The gas flow 7 for improving the dispersibility of the conductive microspheres and preventing the overheating of the gas introduction tube and the collision plate is made to flow in the direction of the arrow, and is further formed between the overheating prevention cylinder 3 and the hot air nozzle 1. A hot air flow 8 for thermal expansion flows in the space in the direction of the arrow. Here, the hot air flow 8, the gas fluid 6, and the gas flow 7 are usually flows in the same direction. Inside the overheating prevention cylinder 3, a coolant flow 2 is caused to flow in the direction of the arrow for cooling.
(Manufacturing equipment operation)
In the injection step, the gas fluid 6 including the thermally expandable microspheres is caused to flow through a gas introduction pipe provided with the dispersion nozzle 4 at the outlet and installed inside the hot air flow 8 to inject the gas fluid 6 from the dispersion nozzle 4. .
In the dispersion step, the gas fluid 6 is caused to collide with the collision plate 5 installed in the downstream portion of the dispersion nozzle 4, and the thermally expandable microspheres are operated to be uniformly dispersed in the hot air flow 8. Here, the gas fluid 6 exiting from the dispersion nozzle 4 is guided toward the collision plate 5 together with the gas flow 7 and collides with it.
In the expansion step, the dispersed thermally expandable microspheres are heated and expanded in the hot air flow 8 to a temperature higher than the expansion start temperature. Thereafter, the obtained hollow fine particles are collected by passing them through a cooling part.
(Method for setting manufacturing conditions for hollow fine particles)
First, parameters such as the supply amount of the heat-expandable microspheres that are raw materials, the flow rate of hot air and the amount of raw material dispersed gas are fixed, and the temperature of the hot air flow (hereinafter sometimes referred to as “hot air temperature”) is changed. . Next, while changing the hot air temperature stepwise and fixing other parameters constant, the thermally expandable microspheres were expanded at each temperature, and the true specific gravity of the obtained microspheres was measured, and the hot air temperature ( A graph in which the relationship between the x axis) and the true specific gravity (y axis) is plotted is created.
When producing expanded microspheres having a desired true specific gravity ((0.025 ± 0.001) g / cc), the hot air temperature corresponding to the desired true specific gravity in the above graph is set. In this way, expansion conditions are controlled, and hollow fine particles having a true specific gravity of (0.025 ± 0.001) g / cc are produced.
(Measurement of repeated compression durability)
2.00 mg of the hollow fine particles obtained above are put in an aluminum cup having a diameter of 6 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, and an aluminum lid having a diameter of 5.6 mm and a thickness of 0.1 mm is placed on the hollow fine particle layer. Use the sample as a sample. Next, using a DMA (DMAQ800 type, manufactured by TA instruments), the height of the hollow fine particle layer in a state in which a force of 2.5 N was applied to the sample from the top of the aluminum lid with a pressurizer in an environment of 25 ° C. the L ₁ is measured. Then, after pressing the hollow fine particle layer from 2.5 N to 18 N at a speed of 10 N / min and then depressurizing from 18 N to 2.5 N at a speed of 10 N / min, the operation was repeated 8 times, and then the aluminum cap was pressed with the pressurizer. measuring the height L ₂ of the hollow fine particle layer in a state where the upper a force of 2.5 N. Then, as shown in the following formula, the ratio of the measured height L ₁ and L _{2 of} the hollow fine particle layer is repeatedly defined as compression durability.
Repeated compression durability (%) = (L ₂ / L ₁ ) × 100
[Measurement of density of molded product]
The density of the molded product was measured using an upper plate electronic analysis balance AX200 and a specific gravity measurement kit SMK-301 manufactured by Shimadzu Corporation.
[Calculation of the weight reduction rate of foamed moldings]
In the same manner as in the measurement of the above molding, foam molding density D _{B (g} / cm ³⁾ was measured heat-expandable microspheres is not added resin density ^{_{D A (g / cm 3)}} , the following equation that value Introduced and calculated.
Weight reduction rate (%) = ((D _A −D _B × 100 / D _A )
[Example A1]
It is obtained after adding 100 g of sodium chloride, 80 g of colloidal silica having an active silica content of 20% by weight, 0.1 g of polyvinylpyrrolidone and 0.5 g of 1% aqueous solution of ethylenediaminetetraacetic acid and 4Na salt to 600 g of ion-exchanged water. The pH of the obtained mixture was adjusted to 2.8 to 3.2 to prepare an aqueous dispersion medium.
Separately, 180 g of acrylonitrile, 105 g of methacrylonitrile, 15 g of methyl methacrylate, 1.5 g of ethylene glycol dimethacrylate, 75 g of isopentane and 1 g of 2,2′-azobisisobutyronitrile were mixed to prepare an oily mixture. The aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed with a homomixer (TK machine, manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotational speed of 5000 rpm for 5 minutes to prepare a suspension. The suspension was transferred to a pressure reactor having a capacity of 1.5 liters, and purged with nitrogen. Then, the initial reaction pressure was 0.5 MPa, and polymerization was performed at a polymerization temperature of 70 ° C. for 20 hours while stirring at 80 rpm. After polymerization, the polymerization product was filtered and dried to obtain thermally expandable microspheres.
The stability of the suspension during the polymerization reaction was good, and there was no abnormality in the reaction mixture after polymerization, and it was in a good state. Further, when the reaction solution was extracted after the polymerization, no polymer deposit was observed on the inner wall of the reaction vessel. The physical properties of the obtained thermally expandable microspheres are shown in Table 1.
[Examples A2 to A22 and Comparative Examples A1 to A9]
In Examples A2 to A22 and Comparative Examples A1 to A9, polymerization was performed in the same manner as in Example A1 except that the reaction conditions in Example A1 were changed as shown in Tables 1 to 7, and thermally expandable microspheres were obtained. Respectively.
The results of physical properties and the like of the obtained thermally expandable microspheres are also shown in Tables 1 to 7 as in Example A1. In Comparative Examples A1 to A3, since most of the obtained polymerization products were aggregated / solidified, various physical properties of the obtained thermally expanded four microspheres could not be measured.
[Example B1]
In 600 g of ion-exchanged water, 100 g of sodium chloride, 80 g of colloidal silica having an active silica content of 20% by weight, 0.1 g of polyvinyl pyrrolidone, and aluminum chloride hexahydrate (AlCl ₃ .6H ₂ O) as a water-soluble compound After adding 0.5 g of 1% aqueous solution, the pH of the resulting mixture was adjusted to 2.8 to 3.2 to prepare an aqueous dispersion medium. In addition, the aluminum ion contained in the aqueous dispersion medium was 1.7 ppm, and the chlorine ion was 1.0 × 10 ⁵ ppm.
Separately, 180 g of acrylonitrile, 105 g of methacrylonitrile, 15 g of methyl methacrylate, 1.5 g of ethylene glycol dimethacrylate, 75 g of isopentane and 1 g of 2,2′-azobisisobutyronitrile were mixed to prepare an oily mixture. The aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed with a homomixer (TK machine, manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotational speed of 5000 rpm for 5 minutes to prepare a suspension. The suspension was transferred to a pressure reactor having a capacity of 1.5 liters, and purged with nitrogen. Then, the initial reaction pressure was 0.5 MPa, and polymerization was performed at a polymerization temperature of 70 ° C. for 20 hours while stirring at 80 rpm. After polymerization, the polymerization product was filtered and dried to obtain thermally expandable microspheres.
The stability of the suspension during the polymerization reaction was good, and there was no abnormality in the reaction mixture after polymerization, and it was in a good state. Further, when the reaction solution was extracted after the polymerization, no polymer deposit was observed on the inner wall of the reaction vessel. Table 8 shows the physical properties of the obtained thermally expandable microspheres.
[Examples B2 to B9 and Comparative Examples B1 to B4]
In Examples B2 to B9 and Comparative Examples B1 to B3, polymerization was carried out in the same manner as in Example B1 except that the reaction conditions were changed as shown in Table 8 and Table 9 in Example B1. Each sphere was obtained.
The results of physical properties and the like of the obtained thermally expandable microspheres are also shown in Table 8 and Table 9, respectively. In Comparative Examples B1 to B3, since most of the obtained polymerization products were aggregated / solidified, various physical properties of the obtained thermally expandable microspheres could not be measured.
As in Comparative Example B4, good results were obtained with sodium nitrite, but when the obtained reaction slurry was devolatilized, about 90 ppm of nitrite ions was detected in the filtrate. In this nitrite ion concentration, the total amount of nitrite nitrogen and nitrate nitrogen determined for the amount of harmful substances contained in groundwater in the Enforcement Regulations of the Water Pollution Control Law does not satisfy the standard value of 10 ppm. Or the adsorption process by activated carbon or an ion exchange resin was further required.
[Example C1]
In 600 g of ion-exchanged water, 20 g of sodium chloride, 80 g of colloidal silica having an active silica content of 20% by weight, 3 g of diethanolamine-adipic acid condensate (50% by weight), 20 g of 2-carboxypyridine 1% aqueous solution and ethylenediaminepentaacetic acid. After adding 10 g of 1% aqueous solution of 5Na salt, the pH of the resulting mixture was adjusted to 2.8-3.2 to prepare an aqueous dispersion medium.
Separately, 160 g of acrylonitrile, 100 g of methyl methacrylate, 40 g of methyl acrylate, 1.0 g of ethylene glycol dimethacrylate, 80 g of isobutane, and 2 g of g-2-ethylexyl peroxydicarbonate were prepared to prepare an oily mixture. The aqueous dispersion medium and the oily mixture were mixed, and the obtained mixed solution was dispersed for 5 minutes at a rotation speed of 8000 rpm with a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a suspension. This suspension was transferred to a 1.5 liter pressurized reactor and purged with nitrogen, then the initial reaction pressure was 0.5 MPa, and polymerization was carried out at a polymerization temperature of 55 ° C. for 20 hours while stirring at 80 rpm. After polymerization, the polymerization product was filtered and dried to obtain thermally expandable microspheres.
The stability of the suspension during the polymerization reaction was good, and there was no abnormality in the reaction mixture after polymerization, and it was in a good state. Further, when the reaction solution was extracted after the polymerization, no polymer deposit was observed on the inner wall of the reaction vessel. Table 10 shows the physical properties of the obtained thermally expandable microspheres.
[Examples C2 to C6]
In Examples C2 to C6, thermal expansion microspheres were obtained by polymerization in the same manner as in Example C1, except that the reaction conditions in Example C1 were changed as shown in Table 10.
The results of physical properties and the like of the obtained heat-expandable microspheres are also shown in Table 10 as in Example C1.

In the above table, the following abbreviations are used.
* 1: abnormal reaction mixture after the polymerization is not good * 2: Most aggregation / solidification EDTA in the reaction mixture after polymerization: ethylenediaminetetraacetic acid salt · 4Na · _4H 2 O (Chelest Co., Ltd., trade name: Chelest 3D )
GLDA: Dicarboxymethyl glutamic acid · 4Na (manufactured by Kirest Co., Ltd., trade name: Kirest CMG-40)
PBTC: Phosphonobutane triacetic acid 3Na (manufactured by Kirest Co., Ltd., trade name: Kirest PH-430)
EDTMP: Tetrakis (phosphonomethyl) ethylenediamine (manufactured by Kirest Co., Ltd., trade name: Kirest PH-540)
Tannin: Tannic acid (Wako Pure Chemical Industries, Ltd.)
Vitamin B ₆ hydrochloride: Pyridoxine hydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.)
Gallic acid: Gallic acid hydrate (Wako Pure Chemical Industries, Ltd.)
Potassium dichromate: Potassium dichromate (Wako Pure Chemical Industries, Ltd.)
DTPA: Diethylenetriaminepentaacetic acid, 5Na (manufactured by Nagase ChemteX Corporation, trade name: Clewat DP-80)
Thiodiglycolic acid: manufactured by Wako Pure Chemical Industries, Ltd. 2-hydroxypyridine: produced by Wako Pure Chemical Industries, Ltd. 2-carboxypyridine: manufactured by Wako Pure Chemical Industries, Ltd., trade name: 2-pyridinecarboxylic acid Vitamin B _2: Riboflavin (Product name: Vitamin B ₂ manufactured by Wako Pure Chemical Industries, Ltd.)
Adipic acid-diethanolamine condensate: 50% aqueous solution AN: acrylonitrile MAN: methacrylonitrile MMA: methyl methacrylate MA: methyl acrylate VCl ₂ : vinylidene chloride IBX: isobornyl methacrylate MAA: methacrylic acid PMI: N-phenylmaleimide (stock) (Manufactured by Nippon Shokubai)
EDMA: Diethylene glycol dimethacrylate (Mitsubishi Rayon Co., Ltd.)
TMP: Trimethylolpropane trimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd.)
4EG-A: PEG # 200 dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd.)
AIBN: 2,2′-azoisobutyl nitrile (manufactured by Nippon Hydrazine Kogyo Co., Ltd.) S (BP): di-sec-butyl peroxydicarbonate (Lupazole 225 or S (BP), purity 50%, Arkema Yoshiaki Co., Ltd. ) Made)
OPP: Di-2-ethylhexyl peroxydicarbonate (paroyl OPP, purity 70%, manufactured by NOF Corporation)
IPP: Diisopropyl peroxydicarbonate (Perroyl IPP-50, purity 50%, manufactured by NOF Corporation)
[Example D1]
Supermixer (Kawata Co., Ltd.) containing 3% by weight of thermally expandable microspheres obtained in Example A13 and 97% by weight of polypropylene (density 0.9 g / cm ³ , melt flow rate 14 g / 10 minutes (230 ° C.)) And mixed for about 1 minute at a stirring speed (about 360 rpm) that does not increase the temperature to 60 ° C. or higher. The obtained mixture was injection-molded at an injection pressure of about 1000 kg / cm ² using an injection molding machine having a clamping force of about 80 tons and a screw diameter of 32 mm to obtain a disk-shaped molded product having a diameter of 98 mm × 3 mm. . The temperature conditions were 190 ° C., 210 ° C., 230 ° C., and 250 ° C., and the density of the obtained molded product was measured and the weight reduction rate was calculated. The results are shown in Table 11.
[Comparative Example D1]
In Example D1, a molded product was obtained in the same manner as in Example D1, except that the thermally expandable microspheres obtained in Comparative Example A4 were used instead of the thermally expandable microspheres obtained in Example A13. The results are shown in Table 11.
[Example D2]
(Method for producing masterbatch containing 30% by weight of thermally expandable microspheres)
30% by weight of thermally expandable microspheres obtained in Example A13 and 70% by weight of polyethylene (manufactured by Dow Chemical Japan, ENGAGE SM8400, density 0.9 g / cm ³ , DSC melting point 63.3 ° C.) 2% by weight of paraffin oil (150S) was put into a super mixer (manufactured by Kawata Co., Ltd.) and mixed for about 1 min at a stirring speed (about 360 rpm) that did not raise the temperature to 60 ° C. or higher.
The obtained mixture was put into a twin screw extruder (Ikegai Co., Ltd .; GT-110), kneaded under the conditions of a screw rotation speed of 30 rpm and a die part temperature of 90 ° C., and a diameter of 3 to 3.5 mm. Extruded. The mixture extruded from the die was immediately hot cut with a rotary hammer attached to the die outlet. Furthermore, the pellets immediately after hot cutting were put into a pellet cooler equipped with a hexagonal rotating body, and cooled to a temperature of 50 ° C. or lower while rotating. Thus, a masterbatch containing 30% by weight of the thermally expandable microspheres obtained in Example A13 having a diameter of 3 to 3.5 mm and a length of 2 to 4 mm was produced.
(Production of foam molded products)
The foam molded article in Example D2 was prepared by using 10% by weight of the masterbatch and 90% by weight of polypropylene instead of using the mixture of 3% by weight of thermally expandable microspheres of Example D1 and 97% by weight of polypropylene as raw materials. This was carried out in the same manner as in Example D1, except that the above mixture was used as a raw material. The density of the obtained molding was measured and the weight reduction rate was calculated. The results are shown in Table 11.
[Comparative Example D2]
In Comparative Example D2, a foam-molded article was prepared in the same manner as in Example D2, except that the thermally expandable microspheres obtained in Comparative Example A4 were used instead of the thermally expandable microspheres obtained in Example A13. Produced. The density of the obtained molding was measured and the weight reduction rate was calculated. The results are shown in Table 11.

From the results shown in Table 11, when the thermally expandable microspheres of the present invention are used for reducing the weight of the resin, they have a very excellent weight reduction performance, and also have a very high durability against mixed stress during the production of a masterbatch. It is clear.
[Example D3]
(Method for producing hollow fine particles)
An aqueous dispersion (slurry) containing 5% by weight of the heat-expandable microspheres obtained in Example A21 was prepared. This aqueous dispersion was expanded by a wet heating expansion method described in Japanese Patent Application Laid-Open No. Sho 62-201231 to obtain hollow fine particles. Details are shown below.
The slurry is sent from the slurry introduction tube to the foaming tube (diameter 16 mm volume 120 ml, made of SUS304TP) at a flow rate of 5 L / min, and further steam (temperature: 147 ° C., pressure: 0.3 MPa) is supplied from the steam introduction tube. The mixture was mixed with the slurry and expanded by wet heating. The slurry temperature after mixing was adjusted to 120 ° C., and the pressure was 0.18 MPa.
The obtained slurry containing hollow fine particles was allowed to flow out from the foaming tube protrusion, mixed with cooling water (water temperature 15 ° C.), and cooled to 50 to 60 ° C. The cooled slurry was dehydrated with a centrifugal dehydrator to obtain a composition (containing 15% by weight of water) containing wet hollow fine particles.
A ceramic composition is prepared by kneading 283 g of cordierite, 14.2 g of methyl cellulose and 42.5 g of the composition obtained above as ceramic raw materials, and then the obtained ceramic composition is produced by extrusion molding. After shaping, an unfired ceramic molded body (kneaded material) was formed.
Next, the clay density of the obtained ceramic molded body (kneaded clay) is measured by the following method, at the time of mixing the hollow fine particles and the ceramic material, and at the time of extrusion molding of the composition comprising the hollow fine particles and the ceramic material. Durability against fracture due to generated stress was evaluated. The results were as shown in Table 12.
(Measurement method of dredged soil density)
After cutting the ceramic molded body (kneaded material) to have a constant volume and measuring its weight, the measured weight is divided by the volume, and the kneaded material density is calculated. The durability against fracture due to stress generated during mixing and extrusion was evaluated. The lower the clay density, the better the durability against fracture due to the stress generated during mixing and extrusion molding of the hollow fine particles.
(Criteria)
◎ ...... The soil density is less than 1.4 g / cm ³ .
○ The soil density is 1.4 g / cm ³ or more and less than 1.6 g / cm ³ .
Δ: The clay density is 1.6 g / cm ³ or more and less than 1.7 g / cm ³ .
X ... The soil density is 1.7 g / cm ³ or more.
[Example D4 and Comparative Examples D3 to D4]
In Example D4 and Comparative Examples D3 to D4, evaluation was performed in the same manner as in Example D3 except that in Example D3, the thermally expandable microspheres as raw materials were changed as shown in Table 12.

From the results shown in Table 12, it is clear that the hollow fine particles obtained from the thermally expandable microspheres of the present invention have very excellent performance when mixed with an inorganic material such as a ceramic material.
[Example D5]
A scale-up reaction was carried out at the same blending ratio and reaction conditions as in Example B1 to obtain 20 kg of dry thermally expandable microspheres. The physical properties of the thermally expandable microspheres were equivalent to the thermally expandable microspheres obtained in Example B1.
2 kg of the heat-expandable microspheres obtained above and 8 kg of heavy calcium carbonate (Shiraishi Calcium Co., Ltd., Whiten SB red, average particle size: 1.8 μm) are mixed with an SV mixer (Shinko Environmental Solution Co., Ltd. : 30 L) and mixed for 10 minutes. Thereafter, the obtained mixture was put into a Laedige mixer (manufactured by Matsubo Co., Ltd.), heated at a jacket temperature of 190 ° C. for 10 minutes, and cooled when the temperature of the mixture reached 150 ° C. to obtain a composition. (Average particle diameter: 108 μm, true specific gravity: 0.15 g / cc).
Using the obtained composition, repeated compression durability of the hollow fine particles was evaluated.
The measurement method was the same as the above [Measurement of repeated compression durability] except that 10.0 mg of the above composition was used instead of 2.00 mg of hollow fine particles. The results are shown in Table 13.
[Comparative Example D5]
Comparative Example D5 was performed in the same manner as Example D5, except that thermally expandable microspheres were prepared at the blending ratio of Comparative Example B4 instead of preparing thermally expandable microspheres at the blending ratio of Example B1. The results are shown in Table 13.

From the results of Table 13, it is clear that the composition using the thermally expandable microspheres of the present invention as a raw material also exhibits very good performance in the repeated compression durability.
[Example D6]
(Preparation of unexpanded coating)
10% by weight of the thermally expandable microspheres obtained in Example A17 was added to an ethylene / vinyl acetate copolymer (EVA; ethylene / vinyl acetate = 30/70% by weight) having a concentration of 55% by weight (EVA 9% by weight). 1 parts by weight of thermally expansible microspheres per part) was prepared. This coating solution is applied to double-sided art paper with a coater having a gap of 200 μm. The coated double-sided art paper was dried to prepare a 200 μm-thick unexpanded coating film containing 10% by weight of the thermally expandable microspheres obtained in Example A17 on the double-sided art paper.
(Preparation of expanded coating)
The double-sided art paper on which the unexpanded coating film was formed was heated in a gear-type oven at a predetermined temperature for a predetermined time to obtain a double-sided art paper on which an expanded coating film was formed.
(Measurement method of expansion ratio)
The thickness ratio (B / A) before and after foaming was measured by measuring the thickness (A) of the double-sided art paper on which the unexpanded coating film was formed and the thickness (B) of the double-sided art paper on which the expansion coating was formed. Was calculated and the design properties were evaluated. The results are shown in Table 14. The higher the thickness magnification, the better the design.
[Examples D7 to D8 and Comparative Examples D6 to D7]
In Examples D7 to D8 and Comparative Examples D6 to D7, evaluation was performed in the same manner as in Example D6 except that in Example D6, the thermally expandable microspheres as raw materials were changed as shown in Table 13. .

From the results shown in Table 14, it is clear that the expanded coating film obtained from the thermally expandable microspheres of the present invention is very rich in thickness and has an excellent design performance.
[Example D9]
(Preparation of unexpanded PVC coating)
25 parts by weight of polyvinyl chloride (PVC) (manufactured by Shin-Daiichi Vinyl Chloride Co., Ltd.), 50 parts by weight of DINP (manufactured by Shin Nippon Rika Co., Ltd.) and carbonic acid per 1 part by weight of the thermally expandable microspheres obtained in Example A17 A compound was prepared by adding 25 parts by weight of calcium (manufactured by Bihoku Powder Chemical Co., Ltd.). The prepared compound was coated on a Teflon sheet (EGF-500-10) laid on a 1.5 mm thick 0.8 mm thick electrodeposited iron plate and heated at 100 ° C. for 10 minutes in a gear oven. Gelled and peeled from the Teflon sheet. Thus, the unexpanded PVC coating film was produced.
(Production of expanded PVC coating)
The unexpanded PVC coating was heated in a gear oven at a predetermined temperature for a predetermined time to obtain an expanded PVC coating.
(Measurement method of expansion ratio)
The specific gravity (A) of the unexpanded PVC coating and the specific gravity (B) of the expanded PVC coating were measured, and the specific gravity reduction rate before and after foaming (= (A−B) * 100 / A) was calculated. Evaluated. The results are shown in Table 15. The greater the specific gravity reduction rate, the better the physical properties such as weight reduction, cushioning properties, elasticity, and impact strength.
[Examples D10 to D11 and Comparative Examples D8 to D9]
In Examples D10 to D11 and Comparative Examples D8 to D9, evaluation was performed in the same manner as in Example D9 except that in Example D9, the thermally expandable microspheres as raw materials were changed as shown in Table 15. .

From the results of Table 15, it is clear that the expanded PVC coating obtained from the thermally expandable microspheres of the present invention has very excellent performance in physical properties such as weight reduction, cushioning properties, elasticity and impact strength. .
[Example D12]
(Preparation of unexpanded acrylic coating)
For 1 part by weight of the thermally expandable microspheres obtained in Example A17, 50 parts by weight of methacrylic resin powder (manufactured by Nippon Zeon Co., Ltd.), 40 parts by weight of acetyltributyl citrate, and calcium carbonate (manufactured by Bihoku Powder Chemical Co., Ltd.) A compound was prepared by adding 10 parts by weight. The prepared compound was coated on a Teflon sheet (EGF-500-10) laid on a 1.5 mm thick 0.8 mm thick electrodeposited iron plate and heated at 100 ° C. for 10 minutes in a gear oven. Gelled and peeled from the Teflon sheet. In this way, an unexpanded acrylic coating film was produced.
(Production of expanded acrylic coating)
The unexpanded acrylic coating film was heated in a gear oven at a predetermined temperature for a predetermined time to obtain an expanded acrylic coating film.
(Measurement method of expansion ratio)
The specific gravity (A) of the unexpanded acrylic coating film and the specific gravity (B) of the expanded acrylic coating film were measured, and the specific gravity reduction rate before and after foaming (= (A−B) * 100 / A) was calculated. Evaluated. The results are shown in Table 16. The greater the specific gravity reduction rate, the better the physical properties such as weight reduction, cushioning properties, elasticity, and impact strength.
[Examples D13 to D14 and Comparative Examples D10 to D11]
In Examples D13 to D14 and Comparative Examples D10 to D11, evaluation was performed in the same manner as in Example D12 except that in Example D12, the thermally expandable microspheres as raw materials were changed as shown in Table 16. .

From the results of Table 16, it is clear that the expanded acrylic coating film obtained from the thermally expandable microspheres of the present invention has very excellent performance in physical properties such as weight reduction, cushioning properties, elasticity, and impact strength. .

The thermally expandable microspheres of the present invention have a high expansion ratio, and hollow particles having excellent repeated compression durability when thermally expanded can be obtained. Therefore, it is useful in applications intended to improve designability, porosity, weight reduction, sound absorption, heat insulation / thermal conductivity, impact absorption, and the like.
The method for producing thermally expandable microspheres of the present invention can efficiently produce the above thermally expandable microspheres.

Claims (25)

A method for producing thermally expandable microspheres comprising an outer shell made of a thermoplastic resin, and a foaming agent encapsulated therein and having a boiling point not higher than the softening point of the thermoplastic resin,
Water-soluble polyphenols;
At least one water-soluble vitamin B selected from vitamin B ₂ , vitamin B ₆ , its derivatives and inorganic salts; and a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group and a phosphonic acid (salt) group And an aqueous dispersion medium containing at least one water-soluble compound selected from water-soluble 1,1-substituted compounds having a structure in which a hetero atom and a hetero atom are bonded to the same carbon atom. A method for producing thermally expandable microspheres, comprising a step of dispersing an oily mixture containing a polymer and polymerizing the polymerizable component contained in the oily mixture.   The water-soluble compound is a water-soluble 1,1-substituted compound, the hydrophilic functional group is a carboxylic acid (salt) group and / or a phosphonic acid (salt) group, and the hetero atom is a nitrogen atom and / or a sulfur atom. The method for producing thermally expandable microspheres according to claim 1, wherein The water-soluble compound is tannin, gallic acid, vitamin B ₂ , vitamin B ₆ , ethylenediaminetetraacetic acid (including its salt), hydroxyethylethylenediaminetriacetic acid (including its salt), diethylenetriaminepentaacetic acid (including its salt) , Dihydroxyethylethylenediaminediacetic acid (including its salt), 1,3-propanediaminetetraacetic acid (including its salt), triethylenetetraamine hexaacetic acid (including its salt), nitrilotriacetic acid (including its salt) , Gluconic acid (including its salt), hydroxyethyliminodiacetic acid (including its salt), L-aspartic acid-N, N-didiacetic acid (including its salt), dicarboxymethylglutamic acid (including its salt) ), 1,3-diamino-2-hydroxypropanetetraacetic acid (including its salt), dihydroxyethylglycine (its ), Aminotrimethylene phosphonic acid (including its salt), hydroxyethane phosphonic acid (including its salt), dihydroxyethylglycine (including its salt), phosphonobutane triacetic acid (including its salt), methylene phosphonic acid Nitrilotrismethylenephosphonic acid (including its salt), 2-carboxypyridine, orotic acid, quinolinic acid, lutidine acid, isocincomeronic acid, dipicolinic acid, berberic acid, fusaric acid, orotic acid, 2 The method for producing thermally expandable microspheres according to claim 1 or 2, which is at least one selected from -hydroxypyridine, 6-hydroxynicotinic acid, citrazic acid, and thiodiglycolic acid. The thermal expansion property according to any one of claims 1 to 3, wherein the water-soluble compound further comprises a water-soluble metal salt composed of at least one metal selected from aluminum and antimony and / or a hydrate thereof. A method for producing microspheres. A method for producing thermally expandable microspheres comprising an outer shell made of a thermoplastic resin, and a foaming agent encapsulated therein and having a boiling point not higher than the softening point of the thermoplastic resin,
Water-soluble polyphenols;
At least one water-soluble vitamin B selected from vitamin B ₂ , vitamin B ₆ , its derivatives and inorganic salts;
Water-soluble 1,1-substituted compounds having a structure in which a hydrophilic atom selected from a hydroxyl group, a carboxylic acid (salt) group, and a phosphonic acid (salt) group and a hetero atom are bonded to the same carbon atom; and
Water-soluble metal salt composed of at least one metal selected from aluminum and antimony and / or a hydrate thereof
An oily mixture containing the polymerizable component and the blowing agent in an aqueous dispersion medium containing 0.0001 to 0.066 part by weight of at least one water-soluble compound selected from 100 parts by weight of the polymerizable component A method for producing thermally expandable microspheres , comprising the step of dispersing the polymerizable component and polymerizing the polymerizable component contained in the oily mixture . The polymerizable component is a nitrile monomer, (meth) acrylic acid ester monomer, carboxyl group-containing monomer, styrene monomer, vinyl acetate, acrylamide monomer, maleimide monomer And the method for producing thermally expandable microspheres according to any one of claims 1 to 5 , comprising at least one selected from vinylidene chloride. The method for producing thermally expandable microspheres according to claim 6 , wherein the polymerizable component contains a nitrile monomer as an essential component. The method for producing thermally expandable microspheres according to claim 7 , wherein the polymerizable component further contains a carboxyl group-containing monomer. The method for producing thermally expandable microspheres according to claim 7 or 8 , wherein the polymerizable component further contains vinylidene chloride and / or a (meth) acrylic acid ester monomer. The method for producing thermally expandable microspheres according to any one of claims 7 to 9 , wherein the polymerizable component further contains a maleimide monomer. A method for producing thermally expandable microspheres comprising an outer shell made of a thermoplastic resin, and a foaming agent encapsulated therein and having a boiling point not higher than the softening point of the thermoplastic resin,
A polymerizable component and the foaming agent are contained in an aqueous dispersion medium containing a water-soluble metal salt composed of at least one metal selected from aluminum and antimony and / or a water-soluble compound thereof. A step of dispersing an oily mixture and polymerizing the polymerizable component contained in the oily mixture, wherein the polymerizable component is a nitrile monomer, vinylidene chloride, a vinyl ester monomer, (meth) acrylic acid Ester monomers, styrene monomers, acrylamide monomers, maleimide monomers, unsaturated monoolefin monomers, vinyl ether monomers, vinyl ketone monomers and N-vinyl monomers A method for producing thermally expandable microspheres, comprising a monomer component consisting of at least one selected from a monomer. The method for producing thermally expandable microspheres according to claim 11, wherein the polymerizable component includes a monomer component composed of a nitrile monomer and a (meth) acrylic acid ester monomer. The thermally expandable microsphere according to claim 11 or 12 , wherein the polymerizable component includes a monomer component composed of a nitrile monomer, a (meth) acrylic acid ester monomer, and a maleimide monomer. Manufacturing method. The method for producing thermally expandable microspheres according to any one of claims 4 to 5 and 11 to 13 , wherein the water-soluble metal salt is a metal (III) halide. The heat-expandable microparticle according to any one of claims 4 to 5 and 11 to 14 , wherein the water-soluble metal salt is at least one selected from aluminum chloride (III) hexahydrate and antimony (III) chloride. A method of manufacturing a sphere. The production of thermally expandable microspheres according to any one of claims 1 to 4 and 11 to 15 , wherein the amount of the water-soluble compound is 0.0001 to 1.0 part by weight with respect to 100 parts by weight of the polymerizable component. Method. The method for producing thermally expandable microspheres according to any one of claims 1 to 16 , wherein the aqueous dispersion medium at the time of polymerization is acidic or neutral. The oily mixture further contains a peroxydicarbonate as a polymerization initiator, method for producing heat-expandable microspheres according to any one of claims 1 to 17. The peroxydicarbonate is diethyl peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethylper Oxydicarbonate, di-3-methoxybutylperoxydicarbonate, di-sec-butylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-2-octylperoxydicarbonate, dicyclohexylperoxydicarbonate The method for producing thermally expandable microspheres according to claim 18 , which is at least one selected from dibenzyl peroxydicarbonate. The method for producing thermally expandable microspheres according to claim 18 or 19 , wherein a ratio of the peroxydicarbonate to the polymerization initiator is 60% by weight or more. The method for producing thermally expandable microspheres according to any one of claims 1 to 20 , further comprising a step of attaching a fine particle filler to the outer surface of the outer shell. An outer shell made of a thermoplastic resin, a composed thermally expandable microspheres and a foaming agent having a boiling point below the softening point of it is encapsulated and the thermoplastic resin, to claim 1-21 Thermally expandable microspheres obtained by the production method described above, wherein the expansion ratio at the time of maximum expansion is 50 times or more, and the hollow particles obtained by thermal expansion have a repeated compression durability of 88% or more. A heat-expandable microsphere obtained by the method for producing a heat-expandable microsphere according to any one of claims 1 to 21 and / or a hollow obtained by thermally expanding the heat-expandable microsphere according to claim 22. Fine particles. A composition comprising a base component and the thermally expandable microspheres according to claim 22 and / or the hollow microparticles according to claim 23 . A molded product obtained by molding the composition according to claim 24 .

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